[PATCH v10 2/2] i2c: aspeed: support ast2600 i2c new register mode driver

Christophe JAILLET christophe.jaillet at wanadoo.fr
Sat Apr 15 20:05:47 AEST 2023


(resending, my mail client removed some addresses. Sorry for the 
duplicated message for the others)


Le 15/04/2023 à 03:28, Ryan Chen a écrit :
 > Add i2c new register mode driver to support AST2600 i2c
 > new register mode. AST2600 i2c controller have legacy and
 > new register mode. The new register mode have global register
 > support 4 base clock for scl clock selection, and new clock
 > divider mode. The i2c new register mode have separate register
 > set to control i2c master and slave.
 >
 > Signed-off-by: Ryan Chen <ryan_chen at aspeedtech.com>
 > ---

[...]

 > +static u8 ast2600_i2c_recover_bus(struct ast2600_i2c_bus *i2c_bus)
 > +{
 > +    int ret = 0;
 > +    u32 ctrl;
 > +    u32 state;
 > +    int r;
 > +
 > +    dev_dbg(i2c_bus->dev, "%d-bus recovery bus [%x]\n", 
i2c_bus->adap.nr,
 > +        readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF));
 > +
 > +    ctrl = readl(i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
 > +
 > +    writel(ctrl & ~(AST2600_I2CC_MASTER_EN | AST2600_I2CC_SLAVE_EN),
 > +           i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
 > +
 > +    writel(readl(i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL) | 
AST2600_I2CC_MASTER_EN,
 > +           i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
 > +
 > +    reinit_completion(&i2c_bus->cmd_complete);
 > +    i2c_bus->cmd_err = 0;
 > +
 > +    /* Check 0x14's SDA and SCL status */
 > +    state = readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF);
 > +    if (!(state & AST2600_I2CC_SDA_LINE_STS) && (state & 
AST2600_I2CC_SCL_LINE_STS)) {
 > +        writel(AST2600_I2CM_RECOVER_CMD_EN, i2c_bus->reg_base + 
AST2600_I2CM_CMD_STS);
 > +        r = wait_for_completion_timeout(&i2c_bus->cmd_complete, 
i2c_bus->adap.timeout);
 > +        if (r == 0) {
 > +            dev_dbg(i2c_bus->dev, "recovery timed out\n");
 > +            ret = -ETIMEDOUT;
 > +        } else {
 > +            if (i2c_bus->cmd_err) {
 > +                dev_dbg(i2c_bus->dev, "recovery error\n");
 > +                ret = -EPROTO;
 > +            }
 > +        }
 > +    }
 > +
 > +    dev_dbg(i2c_bus->dev, "Recovery done [%x]\n",
 > +        readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF));
 > +    if (readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF) & 
AST2600_I2CC_BUS_BUSY_STS) {
 > +        dev_dbg(i2c_bus->dev, "Can't recovery bus [%x]\n",

recover?

 > +            readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF));
 > +        ret = -EPROTO;
 > +    }
 > +
 > +    writel(ctrl, i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
 > +    return ret;
 > +}
 > +
 > +#ifdef CONFIG_I2C_SLAVE
 > +static void ast2600_i2c_slave_packet_dma_irq(struct ast2600_i2c_bus 
*i2c_bus, u32 sts)
 > +{
 > +    int slave_rx_len;
 > +    u32 cmd = 0;
 > +    u8 value;
 > +    int i = 0;

No need to init

 > +
 > +    sts &= ~(AST2600_I2CS_SLAVE_PENDING);
 > +    /* Handle i2c slave timeout condition */
 > +    if (AST2600_I2CS_INACTIVE_TO & sts) {
 > +        cmd = SLAVE_TRIGGER_CMD;
 > +        cmd |= AST2600_I2CS_RX_DMA_EN;
 > +        writel(AST2600_I2CS_SET_RX_DMA_LEN(I2C_SLAVE_MSG_BUF_SIZE),
 > +               i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
 > +        writel(cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
 > +        writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + 
AST2600_I2CS_ISR);
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_STOP, &value);
 > +        return;
 > +    }
 > +
 > +    sts &= ~(AST2600_I2CS_PKT_DONE | AST2600_I2CS_PKT_ERROR);
 > +
 > +    switch (sts) {
 > +    case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | 
AST2600_I2CS_WAIT_RX_DMA:
 > +    case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_WAIT_RX_DMA:
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_WRITE_REQUESTED, 
&value);
 > +        slave_rx_len = 
AST2600_I2C_GET_RX_DMA_LEN(readl(i2c_bus->reg_base +
 > +                              AST2600_I2CS_DMA_LEN_STS));
 > +        for (i = 0; i < slave_rx_len; i++) {
 > +            i2c_slave_event(i2c_bus->slave, I2C_SLAVE_WRITE_RECEIVED,
 > +                    &i2c_bus->slave_dma_buf[i]);
 > +        }
 > +        writel(AST2600_I2CS_SET_RX_DMA_LEN(I2C_SLAVE_MSG_BUF_SIZE),
 > +                i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
 > +        cmd = SLAVE_TRIGGER_CMD | AST2600_I2CS_RX_DMA_EN;
 > +        break;
 > +    case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_STOP:
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_STOP, &value);
 > +        writel(AST2600_I2CS_SET_RX_DMA_LEN(I2C_SLAVE_MSG_BUF_SIZE),
 > +                i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
 > +        cmd = SLAVE_TRIGGER_CMD | AST2600_I2CS_RX_DMA_EN;
 > +        break;
 > +    case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE_NAK |
 > +            AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
 > +    case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_WAIT_RX_DMA |
 > +            AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
 > +    case AST2600_I2CS_RX_DONE_NAK | AST2600_I2CS_RX_DONE | 
AST2600_I2CS_STOP:
 > +    case AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_RX_DMA | 
AST2600_I2CS_STOP:
 > +    case AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
 > +    case AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_RX_DMA:
 > +    case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | 
AST2600_I2CS_STOP:
 > +        if (sts & AST2600_I2CS_SLAVE_MATCH)
 > +            i2c_slave_event(i2c_bus->slave, 
I2C_SLAVE_WRITE_REQUESTED, &value);
 > +
 > +        slave_rx_len = 
AST2600_I2C_GET_RX_DMA_LEN(readl(i2c_bus->reg_base +
 > +                              AST2600_I2CS_DMA_LEN_STS));
 > +        for (i = 0; i < slave_rx_len; i++) {
 > +            i2c_slave_event(i2c_bus->slave, I2C_SLAVE_WRITE_RECEIVED,
 > +                    &i2c_bus->slave_dma_buf[i]);
 > +        }
 > +        writel(AST2600_I2CS_SET_RX_DMA_LEN(I2C_SLAVE_MSG_BUF_SIZE),
 > +               i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
 > +        if (sts & AST2600_I2CS_STOP)
 > +            i2c_slave_event(i2c_bus->slave, I2C_SLAVE_STOP, &value);
 > +        cmd = SLAVE_TRIGGER_CMD | AST2600_I2CS_RX_DMA_EN;
 > +        break;
 > +
 > +    /* it is Mw data Mr coming -> it need send tx */
 > +    case AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_TX_DMA:
 > +    case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | 
AST2600_I2CS_WAIT_TX_DMA:
 > +        /* it should be repeat start read */
 > +        if (sts & AST2600_I2CS_SLAVE_MATCH)
 > +            i2c_slave_event(i2c_bus->slave, 
I2C_SLAVE_WRITE_REQUESTED, &value);
 > +
 > +        slave_rx_len = 
AST2600_I2C_GET_RX_DMA_LEN(readl(i2c_bus->reg_base +
 > +                              AST2600_I2CS_DMA_LEN_STS));
 > +        for (i = 0; i < slave_rx_len; i++) {
 > +            i2c_slave_event(i2c_bus->slave, I2C_SLAVE_WRITE_RECEIVED,
 > +                    &i2c_bus->slave_dma_buf[i]);
 > +        }
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_READ_REQUESTED,
 > +                &i2c_bus->slave_dma_buf[0]);
 > +        writel(0, i2c_bus->reg_base + AST2600_I2CS_DMA_LEN_STS);
 > +        writel(AST2600_I2CS_SET_TX_DMA_LEN(1),
 > +                i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
 > +        cmd = SLAVE_TRIGGER_CMD | AST2600_I2CS_TX_DMA_EN;
 > +        break;
 > +    case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_WAIT_TX_DMA:
 > +        /* First Start read */
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_READ_REQUESTED,
 > +                &i2c_bus->slave_dma_buf[0]);
 > +        writel(AST2600_I2CS_SET_TX_DMA_LEN(1),
 > +                i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
 > +        cmd = SLAVE_TRIGGER_CMD | AST2600_I2CS_TX_DMA_EN;
 > +        break;
 > +    case AST2600_I2CS_WAIT_TX_DMA:
 > +        /* it should be next start read */
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_READ_PROCESSED,
 > +                &i2c_bus->slave_dma_buf[0]);
 > +        writel(0, i2c_bus->reg_base + AST2600_I2CS_DMA_LEN_STS);
 > +        writel(AST2600_I2CS_SET_TX_DMA_LEN(1),
 > +                i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
 > +        cmd = SLAVE_TRIGGER_CMD | AST2600_I2CS_TX_DMA_EN;
 > +        break;

Having a new line or not after breaks is not consistent.

 > +
 > +    case AST2600_I2CS_TX_NAK | AST2600_I2CS_STOP:
 > +        /* it just tx complete */
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_STOP, &value);
 > +        writel(0, i2c_bus->reg_base + AST2600_I2CS_DMA_LEN_STS);
 > +        writel(AST2600_I2CS_SET_RX_DMA_LEN(I2C_SLAVE_MSG_BUF_SIZE),
 > +               i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
 > +        cmd = SLAVE_TRIGGER_CMD | AST2600_I2CS_RX_DMA_EN;
 > +        break;
 > +    case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE:
 > +        cmd = 0;
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_WRITE_REQUESTED, 
&value);
 > +        break;
 > +    case AST2600_I2CS_STOP:
 > +        cmd = 0;
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_STOP, &value);
 > +        break;
 > +    default:
 > +        dev_dbg(i2c_bus->dev, "unhandled slave isr case %x, sts 
%x\n", sts,
 > +            readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF));
 > +        break;
 > +    }
 > +
 > +    if (cmd)
 > +        writel(cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
 > +    writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + AST2600_I2CS_ISR);
 > +    readl(i2c_bus->reg_base + AST2600_I2CS_ISR);
 > +}
 > +
 > +static void ast2600_i2c_slave_packet_buff_irq(struct ast2600_i2c_bus 
*i2c_bus, u32 sts)
 > +{
 > +    int slave_rx_len = 0;
 > +    u32 cmd = 0;
 > +    u8 value;
 > +    int i = 0;

No need to init;

 > +
 > +    /* due to master slave is common buffer, so need force the 
master stop not issue */
 > +    if (readl(i2c_bus->reg_base + AST2600_I2CM_CMD_STS) & 0xffff) {
 > +        writel(0, i2c_bus->reg_base + AST2600_I2CM_CMD_STS);
 > +        i2c_bus->cmd_err = -EBUSY;
 > +        writel(0, i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
 > +        complete(&i2c_bus->cmd_complete);
 > +    }
 > +
 > +    /* Handle i2c slave timeout condition */
 > +    if (AST2600_I2CS_INACTIVE_TO & sts) {
 > +        writel(SLAVE_TRIGGER_CMD, i2c_bus->reg_base + 
AST2600_I2CS_CMD_STS);
 > +        writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + 
AST2600_I2CS_ISR);
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_STOP, &value);
 > +        i2c_bus->slave_operate = 0;
 > +        return;
 > +    }
 > +
 > +    sts &= ~(AST2600_I2CS_PKT_DONE | AST2600_I2CS_PKT_ERROR);
 > +
 > +    if (sts & AST2600_I2CS_SLAVE_MATCH)
 > +        i2c_bus->slave_operate = 1;
 > +
 > +    switch (sts) {
 > +    case AST2600_I2CS_SLAVE_PENDING | AST2600_I2CS_WAIT_RX_DMA |
 > +         AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | 
AST2600_I2CS_STOP:
 > +    case AST2600_I2CS_SLAVE_PENDING |
 > +         AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | 
AST2600_I2CS_STOP:
 > +    case AST2600_I2CS_SLAVE_PENDING |
 > +         AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_STOP:
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_STOP, &value);
 > +        fallthrough;
 > +    case AST2600_I2CS_SLAVE_PENDING |
 > +         AST2600_I2CS_WAIT_RX_DMA | AST2600_I2CS_SLAVE_MATCH | 
AST2600_I2CS_RX_DONE:
 > +    case AST2600_I2CS_WAIT_RX_DMA | AST2600_I2CS_SLAVE_MATCH | 
AST2600_I2CS_RX_DONE:
 > +    case AST2600_I2CS_WAIT_RX_DMA | AST2600_I2CS_SLAVE_MATCH:
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_WRITE_REQUESTED, 
&value);
 > +        cmd = SLAVE_TRIGGER_CMD;
 > +        if (sts & AST2600_I2CS_RX_DONE) {
 > +            slave_rx_len = 
AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
 > +                                   AST2600_I2CC_BUFF_CTRL));
 > +            for (i = 0; i < slave_rx_len; i++) {
 > +                value = readb(i2c_bus->buf_base + 0x10 + i);
 > +                i2c_slave_event(i2c_bus->slave, 
I2C_SLAVE_WRITE_RECEIVED, &value);
 > +            }
 > +        }
 > +        if (readl(i2c_bus->reg_base + AST2600_I2CS_CMD_STS) & 
AST2600_I2CS_RX_BUFF_EN)
 > +            cmd = 0;
 > +        else
 > +            cmd = SLAVE_TRIGGER_CMD | AST2600_I2CS_RX_BUFF_EN;
 > +
 > +        writel(AST2600_I2CC_SET_RX_BUF_LEN(i2c_bus->buf_size),
 > +                    i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
 > +        break;
 > +    case AST2600_I2CS_WAIT_RX_DMA | AST2600_I2CS_RX_DONE:
 > +        cmd = SLAVE_TRIGGER_CMD;
 > +        slave_rx_len = 
AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
 > +                               AST2600_I2CC_BUFF_CTRL));
 > +        for (i = 0; i < slave_rx_len; i++) {
 > +            value = readb(i2c_bus->buf_base + 0x10 + i);
 > +            i2c_slave_event(i2c_bus->slave, 
I2C_SLAVE_WRITE_RECEIVED, &value);
 > +        }
 > +        cmd |= AST2600_I2CS_RX_BUFF_EN;
 > +        writel(AST2600_I2CC_SET_RX_BUF_LEN(i2c_bus->buf_size),
 > +                        i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
 > +        break;
 > +    case AST2600_I2CS_SLAVE_PENDING | AST2600_I2CS_WAIT_RX_DMA |
 > +                AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
 > +        cmd = SLAVE_TRIGGER_CMD;
 > +        slave_rx_len = 
AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
 > +                               AST2600_I2CC_BUFF_CTRL));
 > +        for (i = 0; i < slave_rx_len; i++) {
 > +            value = readb(i2c_bus->buf_base + 0x10 + i);
 > +            i2c_slave_event(i2c_bus->slave, 
I2C_SLAVE_WRITE_RECEIVED, &value);
 > +        }
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_STOP, &value);
 > +        cmd |= AST2600_I2CS_RX_BUFF_EN;
 > +        writel(AST2600_I2CC_SET_RX_BUF_LEN(i2c_bus->buf_size),
 > +                        i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
 > +        break;
 > +

Having a new line or not after breaks is not consistent.

 > +    case AST2600_I2CS_SLAVE_PENDING | AST2600_I2CS_RX_DONE | 
AST2600_I2CS_STOP:
 > +        cmd = SLAVE_TRIGGER_CMD;
 > +        slave_rx_len = 
AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
 > +                               AST2600_I2CC_BUFF_CTRL));
 > +        for (i = 0; i < slave_rx_len; i++) {
 > +            value = readb(i2c_bus->buf_base + 0x10 + i);
 > +            i2c_slave_event(i2c_bus->slave, 
I2C_SLAVE_WRITE_RECEIVED, &value);
 > +        }
 > +        /* workaround for avoid next start with len != 0 */
 > +        writel(BIT(0), i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_STOP, &value);
 > +        break;
 > +
 > +    case AST2600_I2CS_RX_DONE | AST2600_I2CS_STOP:
 > +        cmd = SLAVE_TRIGGER_CMD;
 > +        slave_rx_len = 
AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
 > +                               AST2600_I2CC_BUFF_CTRL));
 > +        for (i = 0; i < slave_rx_len; i++) {
 > +            value = readb(i2c_bus->buf_base + 0x10 + i);
 > +            i2c_slave_event(i2c_bus->slave, 
I2C_SLAVE_WRITE_RECEIVED, &value);
 > +        }
 > +        /* workaround for avoid next start with len != 0 */
 > +        writel(BIT(0), i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_STOP, &value);
 > +        break;
 > +    case AST2600_I2CS_WAIT_TX_DMA | AST2600_I2CS_SLAVE_MATCH:
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_READ_REQUESTED, 
&value);
 > +        writeb(value, i2c_bus->buf_base);
 > +        writel(AST2600_I2CC_SET_TX_BUF_LEN(1),
 > +                i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
 > +        cmd = SLAVE_TRIGGER_CMD | AST2600_I2CS_TX_BUFF_EN;
 > +        break;
 > +    case AST2600_I2CS_WAIT_TX_DMA | AST2600_I2CS_RX_DONE:
 > +    case AST2600_I2CS_WAIT_TX_DMA:
 > +        if (sts & AST2600_I2CS_RX_DONE) {
 > +            slave_rx_len = 
AST2600_I2CC_GET_RX_BUF_LEN(readl(i2c_bus->reg_base +
 > +                            AST2600_I2CC_BUFF_CTRL));
 > +            for (i = 0; i < slave_rx_len; i++) {
 > +                value = readb(i2c_bus->buf_base + 0x10 + i);
 > +                i2c_slave_event(i2c_bus->slave, 
I2C_SLAVE_WRITE_RECEIVED, &value);
 > +            }
 > +            i2c_slave_event(i2c_bus->slave, 
I2C_SLAVE_READ_REQUESTED, &value);
 > +        } else {
 > +            i2c_slave_event(i2c_bus->slave, 
I2C_SLAVE_READ_PROCESSED, &value);
 > +        }
 > +        writeb(value, i2c_bus->buf_base);
 > +        writel(AST2600_I2CC_SET_TX_BUF_LEN(1),
 > +                i2c_bus->reg_base + AST2600_I2CC_BUFF_CTRL);
 > +        cmd = SLAVE_TRIGGER_CMD | AST2600_I2CS_TX_BUFF_EN;
 > +        break;
 > +    /* workaround : trigger the cmd twice to fix next state keep 
1000000 */
 > +    case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE:
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_WRITE_REQUESTED, 
&value);
 > +        cmd = SLAVE_TRIGGER_CMD | AST2600_I2CS_RX_BUFF_EN;
 > +        writel(cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
 > +        break;
 > +
 > +    case AST2600_I2CS_TX_NAK | AST2600_I2CS_STOP:
 > +    case AST2600_I2CS_STOP:
 > +        cmd = SLAVE_TRIGGER_CMD;
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_STOP, &value);
 > +        break;
 > +    default:
 > +        dev_dbg(i2c_bus->dev, "unhandled slave isr case %x, sts 
%x\n", sts,
 > +            readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF));
 > +        break;
 > +    }
 > +
 > +    if (cmd)
 > +        writel(cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
 > +    writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + AST2600_I2CS_ISR);
 > +    readl(i2c_bus->reg_base + AST2600_I2CS_ISR);
 > +
 > +    if ((sts & AST2600_I2CS_STOP) && !(sts & 
AST2600_I2CS_SLAVE_PENDING))
 > +        i2c_bus->slave_operate = 0;
 > +

Nit: unneeded empty line.

 > +}
 > +
 > +static void ast2600_i2c_slave_byte_irq(struct ast2600_i2c_bus 
*i2c_bus, u32 sts)
 > +{
 > +    u32 i2c_buff = readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF);
 > +    u32 cmd = AST2600_I2CS_ACTIVE_ALL;
 > +    u8 byte_data;
 > +    u8 value;
 > +
 > +    switch (sts) {
 > +    case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | 
AST2600_I2CS_WAIT_RX_DMA:
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_WRITE_REQUESTED, 
&value);
 > +        /* first address match is address */
 > +        byte_data = AST2600_I2CC_GET_RX_BUFF(i2c_buff);
 > +        break;
 > +    case AST2600_I2CS_RX_DONE | AST2600_I2CS_WAIT_RX_DMA:
 > +        byte_data = AST2600_I2CC_GET_RX_BUFF(i2c_buff);
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_WRITE_RECEIVED, 
&byte_data);
 > +        break;
 > +    case AST2600_I2CS_SLAVE_MATCH | AST2600_I2CS_RX_DONE | 
AST2600_I2CS_WAIT_TX_DMA:
 > +        cmd |= AST2600_I2CS_TX_CMD;
 > +        byte_data = AST2600_I2CC_GET_RX_BUFF(i2c_buff);
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_READ_REQUESTED, 
&byte_data);
 > +        writel(byte_data, i2c_bus->reg_base + 
AST2600_I2CC_STS_AND_BUFF);
 > +        break;
 > +    case AST2600_I2CS_TX_ACK | AST2600_I2CS_WAIT_TX_DMA:
 > +        cmd |= AST2600_I2CS_TX_CMD;
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_READ_PROCESSED, 
&byte_data);
 > +        writel(byte_data, i2c_bus->reg_base + 
AST2600_I2CC_STS_AND_BUFF);
 > +        break;
 > +    case AST2600_I2CS_STOP:
 > +    case AST2600_I2CS_STOP | AST2600_I2CS_TX_NAK:
 > +        i2c_slave_event(i2c_bus->slave, I2C_SLAVE_STOP, &value);
 > +        break;
 > +    default:
 > +        dev_dbg(i2c_bus->dev, "unhandled pkt isr %x\n", sts);
 > +        break;
 > +    }
 > +    writel(cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
 > +    writel(sts, i2c_bus->reg_base + AST2600_I2CS_ISR);
 > +    readl(i2c_bus->reg_base + AST2600_I2CS_ISR);
 > +}
 > +
 > +static int ast2600_i2c_slave_irq(struct ast2600_i2c_bus *i2c_bus)
 > +{
 > +    u32 ier = readl(i2c_bus->reg_base + AST2600_I2CS_IER);
 > +    u32 isr = readl(i2c_bus->reg_base + AST2600_I2CS_ISR);
 > +
 > +    if (!(isr & ier))
 > +        return 0;
 > +
 > +    /* Slave interrupt coming after Master package done
 > +     * So need handle master first.
 > +     */
 > +    if (readl(i2c_bus->reg_base + AST2600_I2CM_ISR) & 
AST2600_I2CM_PKT_DONE)
 > +        return 0;
 > +
 > +    isr &= ~(AST2600_I2CS_ADDR_INDICATE_MASK);
 > +
 > +    if (AST2600_I2CS_ADDR1_NAK & isr)
 > +        isr &= ~AST2600_I2CS_ADDR1_NAK;
 > +
 > +    if (AST2600_I2CS_ADDR2_NAK & isr)
 > +        isr &= ~AST2600_I2CS_ADDR2_NAK;
 > +
 > +    if (AST2600_I2CS_ADDR3_NAK & isr)
 > +        isr &= ~AST2600_I2CS_ADDR3_NAK;
 > +
 > +    if (AST2600_I2CS_ADDR_MASK & isr)
 > +        isr &= ~AST2600_I2CS_ADDR_MASK;
 > +
 > +    if (AST2600_I2CS_PKT_DONE & isr) {
 > +        if (i2c_bus->mode == DMA_MODE)
 > +            ast2600_i2c_slave_packet_dma_irq(i2c_bus, isr);
 > +        else
 > +            ast2600_i2c_slave_packet_buff_irq(i2c_bus, isr);
 > +    } else
 > +        ast2600_i2c_slave_byte_irq(i2c_bus, isr);
 > +
 > +    return 1;
 > +}
 > +#endif
 > +
 > +static int ast2600_i2c_do_start(struct ast2600_i2c_bus *i2c_bus)
 > +{
 > +    struct i2c_msg *msg = &i2c_bus->msgs[i2c_bus->msgs_index];
 > +    int xfer_len = 0;
 > +    int i = 0;

No need to init.

 > +    u32 cmd;
 > +
 > +    cmd = AST2600_I2CM_PKT_EN | AST2600_I2CM_PKT_ADDR(msg->addr) | 
AST2600_I2CM_START_CMD;
 > +
 > +    /* send start */
 > +    dev_dbg(i2c_bus->dev, "[%d] %sing %d byte%s %s 0x%02x\n",
 > +        i2c_bus->msgs_index, msg->flags & I2C_M_RD ? "read" : "write",
 > +        msg->len, msg->len > 1 ? "s" : "",
 > +        msg->flags & I2C_M_RD ? "from" : "to", msg->addr);
 > +
 > +    i2c_bus->master_xfer_cnt = 0;
 > +    i2c_bus->buf_index = 0;

[...]

 > +static int ast2600_i2c_master_xfer(struct i2c_adapter *adap,
 > +                      struct i2c_msg *msgs, int num)
 > +{
 > +    struct ast2600_i2c_bus *i2c_bus = i2c_get_adapdata(adap);
 > +    unsigned long timeout;
 > +    int ret = 0;

Looks like this initialization is unneeded.

 > +
 > +    /* If bus is busy in a single master environment, attempt 
recovery. */
 > +    if (!i2c_bus->multi_master &&
 > +        (readl(i2c_bus->reg_base + AST2600_I2CC_STS_AND_BUFF) & 
AST2600_I2CC_BUS_BUSY_STS)) {
 > +        int ret;

No need for an extra 'ret'.

 > +
 > +        ret = ast2600_i2c_recover_bus(i2c_bus);
 > +        if (ret)
 > +            return ret;
 > +    }
 > +
 > +#ifdef CONFIG_I2C_SLAVE
 > +    if (i2c_bus->mode == BUFF_MODE) {
 > +        if (i2c_bus->slave_operate)
 > +            return -EBUSY;
 > +        /* disable slave isr */
 > +        writel(0, i2c_bus->reg_base + AST2600_I2CS_IER);
 > +        if (readl(i2c_bus->reg_base + AST2600_I2CS_ISR) || 
(i2c_bus->slave_operate)) {
 > +            writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + 
AST2600_I2CS_IER);
 > +            return -EBUSY;
 > +        }
 > +    }
 > +#endif
 > +
 > +    i2c_bus->cmd_err = 0;
 > +    i2c_bus->msgs = msgs;
 > +    i2c_bus->msgs_index = 0;
 > +    i2c_bus->msgs_count = num;
 > +    reinit_completion(&i2c_bus->cmd_complete);
 > +    ret = ast2600_i2c_do_start(i2c_bus);
 > +#ifdef CONFIG_I2C_SLAVE
 > +    /* avoid race condication slave is wait and master wait 1st 
slave operate */
 > +    if (i2c_bus->mode == BUFF_MODE)
 > +        writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + 
AST2600_I2CS_IER);
 > +#endif
 > +    if (ret)
 > +        goto master_out;
 > +    timeout = wait_for_completion_timeout(&i2c_bus->cmd_complete, 
i2c_bus->adap.timeout);
 > +    if (timeout == 0) {
 > +        u32 isr = readl(i2c_bus->reg_base + AST2600_I2CM_ISR);
 > +        u32 i2c_status = readl(i2c_bus->reg_base + 
AST2600_I2CC_STS_AND_BUFF);
 > +
 > +        dev_dbg(i2c_bus->dev, "timeout isr[%x], sts[%x]\n", isr, 
i2c_status);
 > +        if (isr || (i2c_status & AST2600_I2CC_TX_DIR_MASK)) {
 > +            u32 ctrl = readl(i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
 > +
 > +            writel(0, i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
 > +            writel(ctrl, i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
 > +#ifdef CONFIG_I2C_SLAVE
 > +            if (ctrl & AST2600_I2CC_SLAVE_EN) {
 > +                u32 cmd = SLAVE_TRIGGER_CMD;
 > +
 > +                if (i2c_bus->mode == DMA_MODE) {
 > +                    cmd |= AST2600_I2CS_RX_DMA_EN;
 > +                    writel(i2c_bus->slave_dma_addr,
 > +                           i2c_bus->reg_base + AST2600_I2CS_RX_DMA);
 > +                    writel(i2c_bus->slave_dma_addr,
 > +                           i2c_bus->reg_base + AST2600_I2CS_TX_DMA);
 > + 
writel(AST2600_I2CS_SET_RX_DMA_LEN(I2C_SLAVE_MSG_BUF_SIZE),
 > +                           i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
 > +                } else if (i2c_bus->mode == BUFF_MODE) {
 > +                    cmd = SLAVE_TRIGGER_CMD;
 > +                } else {
 > +                    cmd &= ~AST2600_I2CS_PKT_MODE_EN;
 > +                }
 > +                writel(cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
 > +            }
 > +#endif
 > +        }
 > +        ret = -ETIMEDOUT;
 > +    } else {
 > +        ret = i2c_bus->cmd_err;
 > +    }
 > +
 > +    dev_dbg(i2c_bus->dev, "bus%d-m: %d end\n", i2c_bus->adap.nr, 
i2c_bus->cmd_err);
 > +
 > +master_out:
 > +    if (i2c_bus->mode == DMA_MODE) {
 > +        kfree(i2c_bus->master_safe_buf);
 > +        i2c_bus->master_safe_buf = NULL;

Alignement.

 > +    }
 > +
 > +    return ret;
 > +}
 > +
 > +static void ast2600_i2c_init(struct ast2600_i2c_bus *i2c_bus)
 > +{
 > +    struct platform_device *pdev = to_platform_device(i2c_bus->dev);
 > +    u32 fun_ctrl = AST2600_I2CC_BUS_AUTO_RELEASE | 
AST2600_I2CC_MASTER_EN;
 > +
 > +    /* I2C Reset */
 > +    writel(0, i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
 > +
 > +    if (of_property_read_bool(pdev->dev.of_node, "multi-master"))
 > +        i2c_bus->multi_master = true;
 > +    else
 > +        fun_ctrl |= AST2600_I2CC_MULTI_MASTER_DIS;
 > +
 > +    /* Enable Master Mode */
 > +    writel(fun_ctrl, i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
 > +    /* disable slave address */
 > +    writel(0, i2c_bus->reg_base + AST2600_I2CS_ADDR_CTRL);
 > +
 > +    /* Set AC Timing */
 > +    writel(ast2600_select_i2c_clock(i2c_bus), i2c_bus->reg_base + 
AST2600_I2CC_AC_TIMING);
 > +
 > +    /* Clear Interrupt */
 > +    writel(0xfffffff, i2c_bus->reg_base + AST2600_I2CM_ISR);
 > +
 > +#ifdef CONFIG_I2C_SLAVE
 > +    /* for memory buffer initial */
 > +    if (i2c_bus->mode == DMA_MODE) {
 > +        i2c_bus->slave_dma_buf = dma_alloc_coherent(i2c_bus->dev, 
I2C_SLAVE_MSG_BUF_SIZE,
 > +                                &i2c_bus->slave_dma_addr, GFP_KERNEL);

dmam_alloc_coherent() could maybe be used here.
This would simplify the remove function and avoid some conditional 
compilation.
This also fixes a leak if i2c_add_adapter() fails in the probe.

It is also likely that doing so, the devm_free_irq() in the remove 
function also becomes redundant and can be removed as well.

 > +        if (!i2c_bus->slave_dma_buf)
 > +            return;
 > +    }
 > +
 > +    writel(0xfffffff, i2c_bus->reg_base + AST2600_I2CS_ISR);
 > +
 > +    if (i2c_bus->mode == BYTE_MODE) {
 > +        writel(0xffff, i2c_bus->reg_base + AST2600_I2CS_IER);
 > +    } else {
 > +        /* Set interrupt generation of I2C slave controller */
 > +        writel(AST2600_I2CS_PKT_DONE, i2c_bus->reg_base + 
AST2600_I2CS_IER);
 > +    }
 > +#endif
 > +}
 > +
 > +#ifdef CONFIG_I2C_SLAVE
 > +static int ast2600_i2c_reg_slave(struct i2c_client *client)
 > +{
 > +    struct ast2600_i2c_bus *i2c_bus = i2c_get_adapdata(client->adapter);
 > +    u32 cmd = SLAVE_TRIGGER_CMD;
 > +
 > +    if (i2c_bus->slave)
 > +        return -EINVAL;
 > +
 > +    dev_dbg(i2c_bus->dev, "slave addr %x\n", client->addr);
 > +
 > +    writel(0, i2c_bus->reg_base + AST2600_I2CS_ADDR_CTRL);
 > +    writel(AST2600_I2CC_SLAVE_EN | readl(i2c_bus->reg_base + 
AST2600_I2CC_FUN_CTRL),
 > +           i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
 > +
 > +    /* trigger rx buffer */
 > +    if (i2c_bus->mode == DMA_MODE) {
 > +        cmd |= AST2600_I2CS_RX_DMA_EN;
 > +        writel(i2c_bus->slave_dma_addr, i2c_bus->reg_base + 
AST2600_I2CS_RX_DMA);
 > +        writel(i2c_bus->slave_dma_addr, i2c_bus->reg_base + 
AST2600_I2CS_TX_DMA);
 > +        writel(AST2600_I2CS_SET_RX_DMA_LEN(I2C_SLAVE_MSG_BUF_SIZE),
 > +               i2c_bus->reg_base + AST2600_I2CS_DMA_LEN);
 > +    } else if (i2c_bus->mode == BUFF_MODE) {
 > +        cmd = SLAVE_TRIGGER_CMD;
 > +    } else {
 > +        cmd &= ~AST2600_I2CS_PKT_MODE_EN;
 > +    }
 > +
 > +    writel(cmd, i2c_bus->reg_base + AST2600_I2CS_CMD_STS);
 > +    i2c_bus->slave = client;
 > +    /* Set slave addr. */
 > +    writel(client->addr | AST2600_I2CS_ADDR1_ENABLE,
 > +            i2c_bus->reg_base + AST2600_I2CS_ADDR_CTRL);

Nit: alignement

 > +
 > +    return 0;
 > +}
 > +
 > +static int ast2600_i2c_unreg_slave(struct i2c_client *slave)
 > +{
 > +    struct ast2600_i2c_bus *i2c_bus = i2c_get_adapdata(slave->adapter);
 > +
 > +    WARN_ON(!i2c_bus->slave);
 > +
 > +    /* Turn off slave mode. */
 > +    writel(~AST2600_I2CC_SLAVE_EN & readl(i2c_bus->reg_base + 
AST2600_I2CC_FUN_CTRL),
 > +           i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
 > +    writel(readl(i2c_bus->reg_base + AST2600_I2CS_ADDR_CTRL) & 
~AST2600_I2CS_ADDR1_MASK,
 > +           i2c_bus->reg_base + AST2600_I2CS_ADDR_CTRL);
 > +
 > +    i2c_bus->slave = NULL;
 > +
 > +    return 0;
 > +}
 > +#endif
 > +
 > +static u32 ast2600_i2c_functionality(struct i2c_adapter *adap)
 > +{
 > +    return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | 
I2C_FUNC_SMBUS_BLOCK_DATA;
 > +}
 > +
 > +static const struct i2c_algorithm i2c_ast2600_algorithm = {
 > +    .master_xfer = ast2600_i2c_master_xfer,
 > +#if IS_ENABLED(CONFIG_I2C_SLAVE)
 > +    .reg_slave = ast2600_i2c_reg_slave,
 > +    .unreg_slave = ast2600_i2c_unreg_slave,
 > +#endif
 > +    .functionality = ast2600_i2c_functionality,
 > +};
 > +
 > +static const struct of_device_id ast2600_i2c_bus_of_table[] = {
 > +    {
 > +        .compatible = "aspeed,ast2600-i2cv2",
 > +    },
 > +    {}
 > +};
 > +
 > +MODULE_DEVICE_TABLE(of, ast2600_i2c_bus_of_table);
 > +
 > +static int ast2600_i2c_probe(struct platform_device *pdev)
 > +{
 > +    struct device_node *np = pdev->dev.of_node;
 > +    struct device *dev = &pdev->dev;
 > +    struct ast2600_i2c_bus *i2c_bus;
 > +    struct resource *res;
 > +    u32 global_ctrl;
 > +    int ret = 0;
 > +
 > +    i2c_bus = devm_kzalloc(dev, sizeof(*i2c_bus), GFP_KERNEL);
 > +    if (!i2c_bus)
 > +        return -ENOMEM;
 > +
 > +    i2c_bus->reg_base = devm_platform_ioremap_resource(pdev, 0);
 > +    if (IS_ERR(i2c_bus->reg_base))
 > +        return PTR_ERR(i2c_bus->reg_base);
 > +
 > +    i2c_bus->rst = devm_reset_control_get_shared(dev, NULL);
 > +    if (IS_ERR(i2c_bus->rst))
 > +        return dev_err_probe(dev, PTR_ERR(i2c_bus->rst), "Missing 
reset ctrl\n");
 > +
 > +    reset_control_deassert(i2c_bus->rst);
 > +
 > +    i2c_bus->global_regs = syscon_regmap_lookup_by_phandle(np, 
"aspeed,global-regs");
 > +    if (IS_ERR(i2c_bus->global_regs))
 > +        return PTR_ERR(i2c_bus->global_regs);
 > +
 > +    regmap_read(i2c_bus->global_regs, AST2600_I2CG_CTRL, &global_ctrl);
 > +    if ((global_ctrl & AST2600_GLOBAL_INIT) != AST2600_GLOBAL_INIT) {
 > +        regmap_write(i2c_bus->global_regs, AST2600_I2CG_CTRL, 
AST2600_GLOBAL_INIT);
 > +        regmap_write(i2c_bus->global_regs, 
AST2600_I2CG_CLK_DIV_CTRL, I2CCG_DIV_CTRL);
 > +    }
 > +
 > +    i2c_bus->slave_operate = 0;
 > +    i2c_bus->dev = dev;
 > +    i2c_bus->mode = BUFF_MODE;
 > +
 > +    if (of_property_read_bool(pdev->dev.of_node, "aspeed,enable-dma"))
 > +        i2c_bus->mode = DMA_MODE;
 > +
 > +    if (i2c_bus->mode == BUFF_MODE) {
 > +        res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
 > +        if (res && resource_size(res) >= 2) {
 > +            i2c_bus->buf_base = devm_ioremap_resource(dev, res);
 > +
 > +            if (!IS_ERR_OR_NULL(i2c_bus->buf_base))
 > +                i2c_bus->buf_size = resource_size(res)/2;
 > +        } else
 > +            i2c_bus->mode = BYTE_MODE;
 > +    }
 > +
 > +    /* i2c timeout counter: use base clk4 1Mhz,
 > +     * per unit: 1/(1000/4096) = 4096us
 > +     */
 > +    ret = of_property_read_u32(dev->of_node,
 > +                            "i2c-scl-clk-low-timeout-us",
 > +                            &i2c_bus->timeout);

Strange layout.

 > +    if (ret < 0)
 > +        i2c_bus->timeout = 0;

Nit: This is not really needed since i2c_bus is kzalloc()'ed.

 > +    else
 > +        i2c_bus->timeout /= 4096;
 > +
 > +    init_completion(&i2c_bus->cmd_complete);
 > +
 > +    i2c_bus->irq = platform_get_irq(pdev, 0);
 > +    if (i2c_bus->irq < 0)
 > +        return i2c_bus->irq;
 > +
 > +    platform_set_drvdata(pdev, i2c_bus);
 > +
 > +    i2c_bus->clk = devm_clk_get(i2c_bus->dev, NULL);
 > +    if (IS_ERR(i2c_bus->clk))
 > +        return dev_err_probe(i2c_bus->dev, PTR_ERR(i2c_bus->clk), 
"Can't get clock\n");
 > +
 > +    i2c_bus->apb_clk = clk_get_rate(i2c_bus->clk);
 > +
 > +    ret = of_property_read_u32(dev->of_node, "clock-frequency", 
&i2c_bus->bus_frequency);
 > +    if (ret < 0) {
 > +        dev_warn(dev, "Could not read clock-frequency property\n");
 > +        i2c_bus->bus_frequency = 100000;
 > +    }
 > +
 > +    /* Initialize the I2C adapter */
 > +    i2c_bus->adap.owner = THIS_MODULE;
 > +    i2c_bus->adap.algo = &i2c_ast2600_algorithm;
 > +    i2c_bus->adap.retries = 0;
 > +    i2c_bus->adap.dev.parent = i2c_bus->dev;
 > +    i2c_bus->adap.dev.of_node = dev->of_node;
 > +    i2c_bus->adap.algo_data = i2c_bus;
 > +    strscpy(i2c_bus->adap.name, pdev->name, sizeof(i2c_bus->adap.name));
 > +    i2c_set_adapdata(&i2c_bus->adap, i2c_bus);
 > +
 > +    ast2600_i2c_init(i2c_bus);
 > +
 > +    ret = devm_request_irq(dev, i2c_bus->irq, ast2600_i2c_bus_irq, 0,
 > +                   dev_name(dev), i2c_bus);
 > +    if (ret < 0)
 > +        return dev_err_probe(dev, ret, "Unable to request irq %d\n", 
i2c_bus->irq);
 > +
 > +    if (of_property_read_bool(dev->of_node, "smbus-alert")) {
 > +        i2c_bus->alert_enable = 1;
 > +        i2c_bus->ara = i2c_new_smbus_alert_device(&i2c_bus->adap, 
&i2c_bus->alert_data);
 > +        if (!i2c_bus->ara)
 > +            dev_warn(dev, "Failed to register ARA client\n");
 > +
 > +        writel(AST2600_I2CM_PKT_DONE | AST2600_I2CM_BUS_RECOVER | 
AST2600_I2CM_SMBUS_ALT,
 > +               i2c_bus->reg_base + AST2600_I2CM_IER);
 > +    } else {
 > +        i2c_bus->alert_enable = 0;
 > +        /* Set interrupt generation of I2C master controller */
 > +        writel(AST2600_I2CM_PKT_DONE | AST2600_I2CM_BUS_RECOVER,
 > +                i2c_bus->reg_base + AST2600_I2CM_IER);
 > +    }
 > +
 > +    ret = i2c_add_adapter(&i2c_bus->adap);

Maybe devm_i2c_add_adapter() + remove function simplification.
This change + dmam_alloc_coherent() above + removing devm_free_irq() 
should, all together, not chnage the order of the remove function IIUIC.

CJ

 > +    if (ret)
 > +        return ret;
 > +
 > +    dev_info(dev, "%s [%d]: adapter [%d khz] mode [%d]\n",
 > +         dev->of_node->name, i2c_bus->adap.nr, 
i2c_bus->bus_frequency / 1000,
 > +         i2c_bus->mode);
 > +
 > +    return 0;
 > +}
 > +
 > +static int ast2600_i2c_remove(struct platform_device *pdev)
 > +{
 > +    struct ast2600_i2c_bus *i2c_bus = platform_get_drvdata(pdev);
 > +
 > +    /* Disable everything. */
 > +    writel(0, i2c_bus->reg_base + AST2600_I2CC_FUN_CTRL);
 > +    writel(0, i2c_bus->reg_base + AST2600_I2CM_IER);
 > +
 > +    i2c_del_adapter(&i2c_bus->adap);
 > +    devm_free_irq(&pdev->dev, i2c_bus->irq, i2c_bus);
 > +
 > +#ifdef CONFIG_I2C_SLAVE
 > +    /* for memory buffer initial */
 > +    if (i2c_bus->mode == DMA_MODE)
 > +        dma_free_coherent(i2c_bus->dev, I2C_SLAVE_MSG_BUF_SIZE,
 > +                i2c_bus->slave_dma_buf, i2c_bus->slave_dma_addr);
 > +#endif
 > +
 > +    return 0;
 > +}
 > +
 > +static struct platform_driver ast2600_i2c_bus_driver = {
 > +    .probe = ast2600_i2c_probe,
 > +    .remove = ast2600_i2c_remove,
 > +    .driver = {
 > +        .name = KBUILD_MODNAME,
 > +        .of_match_table = ast2600_i2c_bus_of_table,
 > +    },
 > +};
 > +module_platform_driver(ast2600_i2c_bus_driver);
 > +
 > +MODULE_AUTHOR("Ryan Chen <ryan_chen at aspeedtech.com>");
 > +MODULE_DESCRIPTION("ASPEED AST2600 I2C Controller Driver");
 > +MODULE_LICENSE("GPL");



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