[PATCH v4 4/4] i2c: aspeed: add DMA mode transfer support
Brendan Higgins
brendanhiggins at google.com
Wed Apr 14 07:32:52 AEST 2021
On Wed, Feb 24, 2021 at 11:04 AM Jae Hyun Yoo
<jae.hyun.yoo at linux.intel.com> wrote:
>
> This commit adds DMA mode transfer support.
>
> Only AST2500 and later versions support DMA mode.
>
> AST2500 has these restrictions:
> - If one of these controllers is enabled
> * UHCI host controller
> * MCTP controller
> I2C has to use buffer mode or byte mode instead
> since these controllers run only in DMA mode and
> I2C is sharing the same DMA H/W with them.
> - If one of these controllers uses DMA mode, I2C
> can't use DMA mode
> * SD/eMMC
> * Port80 snoop
>
> Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo at linux.intel.com>
> ---
> Changes since v3:
> - None
>
> Changes since v2:
> - Refined SoC family dependent xfer mode configuration functions.
>
> Changes since v1:
> - Updated commit message and comments.
> - Refined using abstract functions.
>
> drivers/i2c/busses/i2c-aspeed.c | 265 ++++++++++++++++++++++++++------
> 1 file changed, 216 insertions(+), 49 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
> index ffc52937df26..3e3bb014b027 100644
> --- a/drivers/i2c/busses/i2c-aspeed.c
> +++ b/drivers/i2c/busses/i2c-aspeed.c
> @@ -10,6 +10,8 @@
> #include <linux/bitfield.h>
> #include <linux/clk.h>
> #include <linux/completion.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/dmapool.h>
> #include <linux/err.h>
> #include <linux/errno.h>
> #include <linux/i2c.h>
> @@ -47,6 +49,8 @@
> #define ASPEED_I2C_DEV_ADDR_REG 0x18
> #define ASPEED_I2C_BUF_CTRL_REG 0x1c
> #define ASPEED_I2C_BYTE_BUF_REG 0x20
> +#define ASPEED_I2C_DMA_ADDR_REG 0x24
> +#define ASPEED_I2C_DMA_LEN_REG 0x28
>
> /* Device Register Definition */
> /* 0x00 : I2CD Function Control Register */
> @@ -111,6 +115,8 @@
> #define ASPEED_I2CD_BUS_RECOVER_CMD BIT(11)
>
> /* Command Bit */
> +#define ASPEED_I2CD_RX_DMA_ENABLE BIT(9)
> +#define ASPEED_I2CD_TX_DMA_ENABLE BIT(8)
> #define ASPEED_I2CD_RX_BUFF_ENABLE BIT(7)
> #define ASPEED_I2CD_TX_BUFF_ENABLE BIT(6)
> #define ASPEED_I2CD_M_STOP_CMD BIT(5)
> @@ -136,6 +142,14 @@
> #define ASPEED_I2CD_BUF_TX_COUNT_MASK GENMASK(15, 8)
> #define ASPEED_I2CD_BUF_OFFSET_MASK GENMASK(5, 0)
>
> +/* 0x24 : I2CD DMA Mode Buffer Address Register */
> +#define ASPEED_I2CD_DMA_ADDR_MASK GENMASK(31, 2)
> +#define ASPEED_I2CD_DMA_ALIGN 4
> +
> +/* 0x28 : I2CD DMA Transfer Length Register */
> +#define ASPEED_I2CD_DMA_LEN_SHIFT 0
> +#define ASPEED_I2CD_DMA_LEN_MASK GENMASK(11, 0)
> +
> enum aspeed_i2c_master_state {
> ASPEED_I2C_MASTER_INACTIVE,
> ASPEED_I2C_MASTER_PENDING,
> @@ -161,6 +175,7 @@ struct aspeed_i2c_config {
> u32 (*get_clk_reg_val)(struct device *dev, u32 divisor);
> int (*enable_sram)(void);
> int (*set_buf_xfer_mode)(struct device *dev);
> + int (*set_dma_xfer_mode)(struct device *dev);
> };
>
> struct aspeed_i2c_bus {
> @@ -190,6 +205,12 @@ struct aspeed_i2c_bus {
> void __iomem *buf_base;
> u8 buf_offset;
> u8 buf_page;
> + /* DMA mode */
> + struct dma_pool *dma_pool;
> + dma_addr_t dma_handle;
> + u8 *dma_buf;
> + size_t dma_len;
> + /* Buffer/DMA mode */
> size_t buf_size;
> #if IS_ENABLED(CONFIG_I2C_SLAVE)
> struct i2c_client *slave;
> @@ -272,9 +293,13 @@ static inline void
> aspeed_i2c_slave_handle_rx_done(struct aspeed_i2c_bus *bus, u32 irq_status,
> u8 *value)
> {
> - if (bus->buf_base &&
> + if (bus->dma_buf &&
> bus->slave_state == ASPEED_I2C_SLAVE_WRITE_RECEIVED &&
> !(irq_status & ASPEED_I2CD_INTR_NORMAL_STOP))
> + *value = bus->dma_buf[0];
> + else if (bus->buf_base &&
> + bus->slave_state == ASPEED_I2C_SLAVE_WRITE_RECEIVED &&
> + !(irq_status & ASPEED_I2CD_INTR_NORMAL_STOP))
> *value = readb(bus->buf_base);
> else
> *value = readl(bus->base + ASPEED_I2C_BYTE_BUF_REG) >> 8;
> @@ -288,7 +313,18 @@ aspeed_i2c_slave_handle_normal_stop(struct aspeed_i2c_bus *bus, u32 irq_status,
>
> if (bus->slave_state == ASPEED_I2C_SLAVE_WRITE_RECEIVED &&
> irq_status & ASPEED_I2CD_INTR_RX_DONE) {
> - if (bus->buf_base) {
> + if (bus->dma_buf) {
> + len = bus->buf_size -
> + FIELD_GET(ASPEED_I2CD_DMA_LEN_MASK,
> + readl(bus->base +
> + ASPEED_I2C_DMA_LEN_REG));
> + for (i = 0; i < len; i++) {
> + *value = bus->dma_buf[i];
> + i2c_slave_event(bus->slave,
> + I2C_SLAVE_WRITE_RECEIVED,
> + value);
> + }
> + } else if (bus->buf_base) {
> len = FIELD_GET(ASPEED_I2CD_BUF_RX_COUNT_MASK,
> readl(bus->base +
> ASPEED_I2C_BUF_CTRL_REG));
> @@ -305,7 +341,14 @@ aspeed_i2c_slave_handle_normal_stop(struct aspeed_i2c_bus *bus, u32 irq_status,
> static inline void
> aspeed_i2c_slave_handle_write_requested(struct aspeed_i2c_bus *bus, u8 *value)
> {
> - if (bus->buf_base) {
> + if (bus->dma_buf) {
> + writel(bus->dma_handle & ASPEED_I2CD_DMA_ADDR_MASK,
> + bus->base + ASPEED_I2C_DMA_ADDR_REG);
> + writel(FIELD_PREP(ASPEED_I2CD_DMA_LEN_MASK, bus->buf_size),
> + bus->base + ASPEED_I2C_DMA_LEN_REG);
> + writel(ASPEED_I2CD_RX_DMA_ENABLE,
> + bus->base + ASPEED_I2C_CMD_REG);
> + } else if (bus->buf_base) {
> writel(FIELD_PREP(ASPEED_I2CD_BUF_RX_SIZE_MASK,
> bus->buf_size - 1) |
> FIELD_PREP(ASPEED_I2CD_BUF_OFFSET_MASK,
> @@ -321,7 +364,23 @@ aspeed_i2c_slave_handle_write_received(struct aspeed_i2c_bus *bus, u8 *value)
> {
> int i, len;
>
> - if (bus->buf_base) {
> + if (bus->dma_buf) {
> + len = bus->buf_size -
> + FIELD_GET(ASPEED_I2CD_DMA_LEN_MASK,
> + readl(bus->base +
> + ASPEED_I2C_DMA_LEN_REG));
> + for (i = 1; i < len; i++) {
> + *value = bus->dma_buf[i];
> + i2c_slave_event(bus->slave, I2C_SLAVE_WRITE_RECEIVED,
> + value);
> + }
> + writel(bus->dma_handle & ASPEED_I2CD_DMA_ADDR_MASK,
> + bus->base + ASPEED_I2C_DMA_ADDR_REG);
> + writel(FIELD_PREP(ASPEED_I2CD_DMA_LEN_MASK, bus->buf_size),
> + bus->base + ASPEED_I2C_DMA_LEN_REG);
> + writel(ASPEED_I2CD_RX_DMA_ENABLE,
> + bus->base + ASPEED_I2C_CMD_REG);
> + } else if (bus->buf_base) {
> len = FIELD_GET(ASPEED_I2CD_BUF_RX_COUNT_MASK,
> readl(bus->base +
> ASPEED_I2C_BUF_CTRL_REG));
> @@ -451,7 +510,15 @@ aspeed_i2c_prepare_rx_buf(struct aspeed_i2c_bus *bus, struct i2c_msg *msg)
> command |= ASPEED_I2CD_M_S_RX_CMD_LAST;
> }
>
> - if (bus->buf_base) {
> + if (bus->dma_buf) {
> + command |= ASPEED_I2CD_RX_DMA_ENABLE;
> +
> + writel(bus->dma_handle & ASPEED_I2CD_DMA_ADDR_MASK,
> + bus->base + ASPEED_I2C_DMA_ADDR_REG);
> + writel(FIELD_PREP(ASPEED_I2CD_DMA_LEN_MASK, len),
> + bus->base + ASPEED_I2C_DMA_LEN_REG);
> + bus->dma_len = len;
> + } else {
> command |= ASPEED_I2CD_RX_BUFF_ENABLE;
>
> writel(FIELD_PREP(ASPEED_I2CD_BUF_RX_SIZE_MASK, len - 1) |
> @@ -474,7 +541,18 @@ aspeed_i2c_prepare_tx_buf(struct aspeed_i2c_bus *bus, struct i2c_msg *msg)
> else
> len = msg->len + 1;
>
> - if (bus->buf_base) {
> + if (bus->dma_buf) {
> + command |= ASPEED_I2CD_TX_DMA_ENABLE;
> +
> + bus->dma_buf[0] = slave_addr;
> + memcpy(bus->dma_buf + 1, msg->buf, len);
> +
> + writel(bus->dma_handle & ASPEED_I2CD_DMA_ADDR_MASK,
> + bus->base + ASPEED_I2C_DMA_ADDR_REG);
> + writel(FIELD_PREP(ASPEED_I2CD_DMA_LEN_MASK, len),
> + bus->base + ASPEED_I2C_DMA_LEN_REG);
> + bus->dma_len = len;
> + } else {
> u8 wbuf[4];
> int i;
>
> @@ -527,18 +605,19 @@ static void aspeed_i2c_do_start(struct aspeed_i2c_bus *bus)
> if (msg->flags & I2C_M_RD) {
> command |= ASPEED_I2CD_M_RX_CMD;
> if (!(msg->flags & I2C_M_RECV_LEN)) {
> - if (msg->len && bus->buf_base)
> + if (msg->len && (bus->dma_buf || bus->buf_base))
> command |= aspeed_i2c_prepare_rx_buf(bus, msg);
>
> /* Need to let the hardware know to NACK after RX. */
> if (msg->len <= 1)
> command |= ASPEED_I2CD_M_S_RX_CMD_LAST;
> }
> - } else if (msg->len && bus->buf_base) {
> + } else if (msg->len && (bus->dma_buf || bus->buf_base)) {
> command |= aspeed_i2c_prepare_tx_buf(bus, msg);
> }
>
> - if (!(command & ASPEED_I2CD_TX_BUFF_ENABLE))
> + if (!(command & (ASPEED_I2CD_TX_BUFF_ENABLE |
> + ASPEED_I2CD_TX_DMA_ENABLE)))
> writel(i2c_8bit_addr_from_msg(msg),
> bus->base + ASPEED_I2C_BYTE_BUF_REG);
> writel(command, bus->base + ASPEED_I2C_CMD_REG);
> @@ -581,42 +660,55 @@ aspeed_i2c_master_handle_tx_first(struct aspeed_i2c_bus *bus,
> {
> u32 command = 0;
>
> - if (bus->buf_base) {
> - u8 wbuf[4];
> + if (bus->dma_buf || bus->buf_base) {
> int len;
> - int i;
>
> if (msg->len - bus->buf_index > bus->buf_size)
> len = bus->buf_size;
> else
> len = msg->len - bus->buf_index;
>
> - command |= ASPEED_I2CD_TX_BUFF_ENABLE;
> + if (bus->dma_buf) {
> + command |= ASPEED_I2CD_TX_DMA_ENABLE;
>
> - if (msg->len - bus->buf_index > bus->buf_size)
> - len = bus->buf_size;
> - else
> - len = msg->len - bus->buf_index;
> + memcpy(bus->dma_buf, msg->buf + bus->buf_index, len);
>
> - /*
> - * Looks bad here again but use dword writings to avoid data
> - * corruption of byte writing on remapped I2C SRAM.
> - */
> - for (i = 0; i < len; i++) {
> - wbuf[i % 4] = msg->buf[bus->buf_index + i];
> - if (i % 4 == 3)
> + writel(bus->dma_handle & ASPEED_I2CD_DMA_ADDR_MASK,
> + bus->base + ASPEED_I2C_DMA_ADDR_REG);
> + writel(FIELD_PREP(ASPEED_I2CD_DMA_LEN_MASK, len),
> + bus->base + ASPEED_I2C_DMA_LEN_REG);
> + bus->dma_len = len;
> + } else {
> + u8 wbuf[4];
> + int i;
> +
> + command |= ASPEED_I2CD_TX_BUFF_ENABLE;
> +
> + if (msg->len - bus->buf_index > bus->buf_size)
> + len = bus->buf_size;
> + else
> + len = msg->len - bus->buf_index;
> +
> + /*
> + * Looks bad here again but use dword writings to avoid
> + * data corruption of byte writing on remapped I2C SRAM.
> + */
> + for (i = 0; i < len; i++) {
> + wbuf[i % 4] = msg->buf[bus->buf_index + i];
> + if (i % 4 == 3)
> + writel(*(u32 *)wbuf,
> + bus->buf_base + i - 3);
> + }
> + if (--i % 4 != 3)
> writel(*(u32 *)wbuf,
> - bus->buf_base + i - 3);
> - }
> - if (--i % 4 != 3)
> - writel(*(u32 *)wbuf,
> - bus->buf_base + i - (i % 4));
> + bus->buf_base + i - (i % 4));
>
> - writel(FIELD_PREP(ASPEED_I2CD_BUF_TX_COUNT_MASK,
> - len - 1) |
> - FIELD_PREP(ASPEED_I2CD_BUF_OFFSET_MASK,
> - bus->buf_offset),
> - bus->base + ASPEED_I2C_BUF_CTRL_REG);
> + writel(FIELD_PREP(ASPEED_I2CD_BUF_TX_COUNT_MASK,
> + len - 1) |
> + FIELD_PREP(ASPEED_I2CD_BUF_OFFSET_MASK,
> + bus->buf_offset),
> + bus->base + ASPEED_I2C_BUF_CTRL_REG);
> + }
>
> bus->buf_index += len;
> } else {
Some of these functions are getting really complex and most of the
logic for the different modes is in different if-else blocks. Could
you look into splitting this into separate functions based on which
mode is being used?
Otherwise, this patch looks good.
> @@ -633,7 +725,14 @@ aspeed_i2c_master_handle_rx(struct aspeed_i2c_bus *bus, struct i2c_msg *msg)
> u8 recv_byte;
> int len;
>
> - if (bus->buf_base) {
> + if (bus->dma_buf) {
> + len = bus->dma_len -
> + FIELD_GET(ASPEED_I2CD_DMA_LEN_MASK,
> + readl(bus->base + ASPEED_I2C_DMA_LEN_REG));
> +
> + memcpy(msg->buf + bus->buf_index, bus->dma_buf, len);
> + bus->buf_index += len;
> + } else if (bus->buf_base) {
> len = FIELD_GET(ASPEED_I2CD_BUF_RX_COUNT_MASK,
> readl(bus->base + ASPEED_I2C_BUF_CTRL_REG));
> memcpy_fromio(msg->buf + bus->buf_index, bus->buf_base, len);
> @@ -650,7 +749,7 @@ aspeed_i2c_master_handle_rx_next(struct aspeed_i2c_bus *bus,
> {
> u32 command = 0;
>
> - if (bus->buf_base) {
> + if (bus->dma_buf || bus->buf_base) {
> int len;
>
> if (msg->len - bus->buf_index > bus->buf_size) {
> @@ -660,14 +759,24 @@ aspeed_i2c_master_handle_rx_next(struct aspeed_i2c_bus *bus,
> command |= ASPEED_I2CD_M_S_RX_CMD_LAST;
> }
>
> - command |= ASPEED_I2CD_RX_BUFF_ENABLE;
> + if (bus->dma_buf) {
> + command |= ASPEED_I2CD_RX_DMA_ENABLE;
>
> - writel(FIELD_PREP(ASPEED_I2CD_BUF_RX_SIZE_MASK,
> - len - 1) |
> - FIELD_PREP(ASPEED_I2CD_BUF_TX_COUNT_MASK, 0) |
> - FIELD_PREP(ASPEED_I2CD_BUF_OFFSET_MASK,
> - bus->buf_offset),
> - bus->base + ASPEED_I2C_BUF_CTRL_REG);
> + writel(bus->dma_handle & ASPEED_I2CD_DMA_ADDR_MASK,
> + bus->base + ASPEED_I2C_DMA_ADDR_REG);
> + writel(FIELD_PREP(ASPEED_I2CD_DMA_LEN_MASK, len),
> + bus->base + ASPEED_I2C_DMA_LEN_REG);
> + bus->dma_len = len;
> + } else {
> + command |= ASPEED_I2CD_RX_BUFF_ENABLE;
> +
> + writel(FIELD_PREP(ASPEED_I2CD_BUF_RX_SIZE_MASK,
> + len - 1) |
> + FIELD_PREP(ASPEED_I2CD_BUF_TX_COUNT_MASK, 0) |
> + FIELD_PREP(ASPEED_I2CD_BUF_OFFSET_MASK,
> + bus->buf_offset),
> + bus->base + ASPEED_I2C_BUF_CTRL_REG);
> + }
> } else {
> if (bus->buf_index + 1 == msg->len)
> command |= ASPEED_I2CD_M_S_RX_CMD_LAST;
> @@ -1287,22 +1396,63 @@ static int aspeed_i2c_25xx_set_buf_xfer_mode(struct device *dev)
> return bus->buf_size ? 0 : -EINVAL;
> }
>
> +static int aspeed_i2c_24xx_set_dma_xfer_mode(struct device *dev)
> +{
> + /* AST24xx doesn't support DMA mode */
> +
> + return -EBADR;
> +}
> +
> +static int aspeed_i2c_25xx_set_dma_xfer_mode(struct device *dev)
> +{
> + struct platform_device *pdev = to_platform_device(dev);
> + struct aspeed_i2c_bus *bus = platform_get_drvdata(pdev);
> + int ret;
> +
> + ret = dma_set_mask(&pdev->dev, DMA_BIT_MASK(32));
> + if (!ret) {
> + bus->buf_size = ASPEED_I2CD_DMA_LEN_MASK >>
> + ASPEED_I2CD_DMA_LEN_SHIFT;
> + bus->dma_pool = dma_pool_create("i2c-aspeed",
> + &pdev->dev,
> + bus->buf_size,
> + ASPEED_I2CD_DMA_ALIGN,
> + 0);
> + if (bus->dma_pool)
> + bus->dma_buf = dma_pool_alloc(bus->dma_pool,
> + GFP_KERNEL,
> + &bus->dma_handle);
> +
> + if (!bus->dma_buf) {
> + ret = -ENOMEM;
> + bus->buf_size = 0;
> + dev_dbg(&pdev->dev, "Cannot allocate DMA buffer\n");
> + dma_pool_destroy(bus->dma_pool);
> + }
> + }
> +
> + return ret;
> +}
> +
> static const struct aspeed_i2c_config ast24xx_config = {
> .get_clk_reg_val = aspeed_i2c_24xx_get_clk_reg_val,
> .enable_sram = aspeed_i2c_24xx_enable_sram,
> .set_buf_xfer_mode = aspeed_i2c_24xx_set_buf_xfer_mode,
> + .set_dma_xfer_mode = aspeed_i2c_24xx_set_dma_xfer_mode,
> };
>
> static const struct aspeed_i2c_config ast25xx_config = {
> .get_clk_reg_val = aspeed_i2c_25xx_get_clk_reg_val,
> .enable_sram = aspeed_i2c_25xx_enable_sram,
> .set_buf_xfer_mode = aspeed_i2c_25xx_set_buf_xfer_mode,
> + .set_dma_xfer_mode = aspeed_i2c_25xx_set_dma_xfer_mode,
> };
>
> static const struct aspeed_i2c_config ast26xx_config = {
> .get_clk_reg_val = aspeed_i2c_25xx_get_clk_reg_val,
> .enable_sram = aspeed_i2c_24xx_enable_sram,
> .set_buf_xfer_mode = aspeed_i2c_25xx_set_buf_xfer_mode,
> + .set_dma_xfer_mode = aspeed_i2c_25xx_set_dma_xfer_mode,
> };
>
> static const struct of_device_id aspeed_i2c_bus_of_table[] = {
> @@ -1324,8 +1474,12 @@ static void aspeed_i2c_set_xfer_mode(struct aspeed_i2c_bus *bus)
> return;
>
> ret = bus->config->enable_sram();
> - if (!ret && !strncasecmp(mode, "buf", 3))
> - ret = bus->config->set_buf_xfer_mode(bus->dev);
> + if (!ret) {
> + if (!strncasecmp(mode, "buf", 3))
> + ret = bus->config->set_buf_xfer_mode(bus->dev);
> + else if (!strncasecmp(mode, "dma", 3))
> + ret = bus->config->set_dma_xfer_mode(bus->dev);
> + }
>
> if (ret)
> dev_dbg(&pdev->dev, "Use default (byte) xfer mode\n");
> @@ -1400,22 +1554,31 @@ static int aspeed_i2c_probe_bus(struct platform_device *pdev)
> */
> ret = aspeed_i2c_init(bus, pdev);
> if (ret < 0)
> - return ret;
> + goto out_free_dma_buf;
>
> irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
> ret = devm_request_irq(&pdev->dev, irq, aspeed_i2c_bus_irq,
> 0, dev_name(&pdev->dev), bus);
> if (ret < 0)
> - return ret;
> + goto out_free_dma_buf;
>
> ret = i2c_add_adapter(&bus->adap);
> if (ret < 0)
> - return ret;
> + goto out_free_dma_buf;
>
> dev_info(bus->dev, "i2c bus %d registered (%s mode), irq %d\n",
> - bus->adap.nr, bus->buf_base ? "buf" : "byte", irq);
> + bus->adap.nr, bus->dma_buf ? "dma" :
> + bus->buf_base ? "buf" : "byte",
> + irq);
>
> return 0;
> +
> +out_free_dma_buf:
> + if (bus->dma_buf)
> + dma_pool_free(bus->dma_pool, bus->dma_buf, bus->dma_handle);
> + dma_pool_destroy(bus->dma_pool);
> +
> + return ret;
> }
>
> static int aspeed_i2c_remove_bus(struct platform_device *pdev)
> @@ -1433,6 +1596,10 @@ static int aspeed_i2c_remove_bus(struct platform_device *pdev)
>
> reset_control_assert(bus->rst);
>
> + if (bus->dma_buf)
> + dma_pool_free(bus->dma_pool, bus->dma_buf, bus->dma_handle);
> + dma_pool_destroy(bus->dma_pool);
> +
> i2c_del_adapter(&bus->adap);
>
> return 0;
> --
> 2.17.1
>
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