[PATCH 4/5] i2c: aspeed: add buffer mode transfer support
Brendan Higgins
brendanhiggins at google.com
Wed Oct 9 07:12:54 AEDT 2019
On Mon, Oct 07, 2019 at 04:13:12PM -0700, Jae Hyun Yoo wrote:
> Byte mode currently this driver uses makes lots of interrupt call
nit: Drop "Byte mode".
> which isn't good for performance and it makes the driver very
> timing sensitive. To improve performance of the driver, this commit
> adds buffer mode transfer support which uses I2C SRAM buffer
> instead of using a single byte buffer.
nit: Please use imperative mood.
> Signed-off-by: Jae Hyun Yoo <jae.hyun.yoo at linux.intel.com>
> Tested-by: Tao Ren <taoren at fb.com>
> ---
> drivers/i2c/busses/i2c-aspeed.c | 297 ++++++++++++++++++++++++++++----
> 1 file changed, 263 insertions(+), 34 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
> index 40f6cf98d32e..37d1a7fa2f87 100644
> --- a/drivers/i2c/busses/i2c-aspeed.c
> +++ b/drivers/i2c/busses/i2c-aspeed.c
> @@ -7,6 +7,7 @@
> * Copyright 2017 Google, Inc.
> */
>
> +#include <linux/bitfield.h>
> #include <linux/clk.h>
> #include <linux/completion.h>
> #include <linux/err.h>
> @@ -19,15 +20,24 @@
> #include <linux/irqchip/chained_irq.h>
> #include <linux/irqdomain.h>
> #include <linux/kernel.h>
> +#include <linux/mfd/syscon.h>
> #include <linux/module.h>
> #include <linux/of_address.h>
> #include <linux/of_irq.h>
> #include <linux/of_platform.h>
> #include <linux/platform_device.h>
> +#include <linux/regmap.h>
> #include <linux/reset.h>
> #include <linux/slab.h>
>
> -/* I2C Register */
> +/* I2C Global Registers */
> +/* 0x00 : I2CG Interrupt Status Register */
> +/* 0x08 : I2CG Interrupt Target Assignment */
> +/* 0x0c : I2CG Global Control Register (AST2500) */
> +#define ASPEED_I2CG_GLOBAL_CTRL_REG 0x0c
> +#define ASPEED_I2CG_SRAM_BUFFER_EN BIT(0)
> +
> +/* I2C Bus Registers */
> #define ASPEED_I2C_FUN_CTRL_REG 0x00
> #define ASPEED_I2C_AC_TIMING_REG1 0x04
> #define ASPEED_I2C_AC_TIMING_REG2 0x08
> @@ -35,14 +45,12 @@
> #define ASPEED_I2C_INTR_STS_REG 0x10
> #define ASPEED_I2C_CMD_REG 0x14
> #define ASPEED_I2C_DEV_ADDR_REG 0x18
> +#define ASPEED_I2C_BUF_CTRL_REG 0x1c
> #define ASPEED_I2C_BYTE_BUF_REG 0x20
>
> -/* Global Register Definition */
> -/* 0x00 : I2C Interrupt Status Register */
> -/* 0x08 : I2C Interrupt Target Assignment */
> -
> /* Device Register Definition */
> /* 0x00 : I2CD Function Control Register */
> +#define ASPEED_I2CD_BUFFER_PAGE_SEL_MASK GENMASK(22, 20)
> #define ASPEED_I2CD_MULTI_MASTER_DIS BIT(15)
> #define ASPEED_I2CD_SDA_DRIVE_1T_EN BIT(8)
> #define ASPEED_I2CD_M_SDA_DRIVE_1T_EN BIT(7)
> @@ -102,6 +110,8 @@
> #define ASPEED_I2CD_BUS_RECOVER_CMD BIT(11)
>
> /* Command Bit */
> +#define ASPEED_I2CD_RX_BUFF_ENABLE BIT(7)
> +#define ASPEED_I2CD_TX_BUFF_ENABLE BIT(6)
> #define ASPEED_I2CD_M_STOP_CMD BIT(5)
> #define ASPEED_I2CD_M_S_RX_CMD_LAST BIT(4)
> #define ASPEED_I2CD_M_RX_CMD BIT(3)
> @@ -112,6 +122,13 @@
> /* 0x18 : I2CD Slave Device Address Register */
> #define ASPEED_I2CD_DEV_ADDR_MASK GENMASK(6, 0)
>
> +/* 0x1c : I2CD Buffer Control Register */
> +/* Use 8-bits or 6-bits wide bit fileds to support both AST2400 and AST2500 */
> +#define ASPEED_I2CD_BUF_RX_COUNT_MASK GENMASK(31, 24)
> +#define ASPEED_I2CD_BUF_RX_SIZE_MASK GENMASK(23, 16)
> +#define ASPEED_I2CD_BUF_TX_COUNT_MASK GENMASK(15, 8)
> +#define ASPEED_I2CD_BUF_OFFSET_MASK GENMASK(5, 0)
> +
> enum aspeed_i2c_master_state {
> ASPEED_I2C_MASTER_INACTIVE,
> ASPEED_I2C_MASTER_PENDING,
> @@ -157,6 +174,11 @@ struct aspeed_i2c_bus {
> int master_xfer_result;
> /* Multi-master */
> bool multi_master;
> + /* Buffer mode */
> + void __iomem *buf_base;
> + size_t buf_size;
> + u8 buf_offset;
> + u8 buf_page;
> #if IS_ENABLED(CONFIG_I2C_SLAVE)
> struct i2c_client *slave;
> enum aspeed_i2c_slave_state slave_state;
> @@ -238,6 +260,7 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
> {
> u32 command, irq_handled = 0;
> struct i2c_client *slave = bus->slave;
> + int i, len;
> u8 value;
>
> if (!slave)
> @@ -260,7 +283,12 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
>
> /* Slave was sent something. */
> if (irq_status & ASPEED_I2CD_INTR_RX_DONE) {
> - value = readl(bus->base + ASPEED_I2C_BYTE_BUF_REG) >> 8;
> + if (bus->buf_base &&
> + bus->slave_state == ASPEED_I2C_SLAVE_WRITE_RECEIVED &&
> + !(irq_status & ASPEED_I2CD_INTR_NORMAL_STOP))
I think checking for the buf_base all over the place makes this really
complicated and hard to read.
It might be better to just split this out and have separate handlers
based on what mode the driver is running in.
> + value = readb(bus->buf_base);
> + else
> + value = readl(bus->base + ASPEED_I2C_BYTE_BUF_REG) >> 8;
> /* Handle address frame. */
> if (bus->slave_state == ASPEED_I2C_SLAVE_START) {
> if (value & 0x1)
> @@ -275,6 +303,20 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
>
> /* Slave was asked to stop. */
> if (irq_status & ASPEED_I2CD_INTR_NORMAL_STOP) {
> + if (bus->slave_state == ASPEED_I2C_SLAVE_WRITE_RECEIVED &&
> + irq_status & ASPEED_I2CD_INTR_RX_DONE) {
> + if (bus->buf_base) {
> + len = FIELD_GET(ASPEED_I2CD_BUF_RX_COUNT_MASK,
> + readl(bus->base +
> + ASPEED_I2C_BUF_CTRL_REG));
It looks like you have a lot of improvements in here unrelated to adding
support for buffer mode.
I really appreciate the improvements, but it makes it harder to
understand what buffer features you are adding vs. what
improvments/modernizations you are making.
Can you split this commit up?
> + for (i = 0; i < len; i++) {
> + value = readb(bus->buf_base + i);
> + i2c_slave_event(slave,
> + I2C_SLAVE_WRITE_RECEIVED,
> + &value);
> + }
> + }
> + }
> irq_handled |= ASPEED_I2CD_INTR_NORMAL_STOP;
> bus->slave_state = ASPEED_I2C_SLAVE_STOP;
> }
> @@ -307,9 +349,36 @@ static u32 aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
> case ASPEED_I2C_SLAVE_WRITE_REQUESTED:
> bus->slave_state = ASPEED_I2C_SLAVE_WRITE_RECEIVED;
> i2c_slave_event(slave, I2C_SLAVE_WRITE_REQUESTED, &value);
> + if (bus->buf_base) {
> + writel(FIELD_PREP(ASPEED_I2CD_BUF_RX_SIZE_MASK,
> + bus->buf_size - 1) |
> + FIELD_PREP(ASPEED_I2CD_BUF_OFFSET_MASK,
> + bus->buf_offset),
> + bus->base + ASPEED_I2C_BUF_CTRL_REG);
> + writel(ASPEED_I2CD_RX_BUFF_ENABLE,
> + bus->base + ASPEED_I2C_CMD_REG);
> + }
> break;
> case ASPEED_I2C_SLAVE_WRITE_RECEIVED:
> i2c_slave_event(slave, I2C_SLAVE_WRITE_RECEIVED, &value);
> + if (bus->buf_base) {
> + len = FIELD_GET(ASPEED_I2CD_BUF_RX_COUNT_MASK,
> + readl(bus->base +
> + ASPEED_I2C_BUF_CTRL_REG));
> + for (i = 1; i < len; i++) {
> + value = readb(bus->buf_base + i);
> + i2c_slave_event(slave,
> + I2C_SLAVE_WRITE_RECEIVED,
> + &value);
> + }
> + writel(FIELD_PREP(ASPEED_I2CD_BUF_RX_SIZE_MASK,
> + bus->buf_size - 1) |
> + FIELD_PREP(ASPEED_I2CD_BUF_OFFSET_MASK,
> + bus->buf_offset),
> + bus->base + ASPEED_I2C_BUF_CTRL_REG);
> + writel(ASPEED_I2CD_RX_BUFF_ENABLE,
> + bus->base + ASPEED_I2C_CMD_REG);
> + }
> break;
> case ASPEED_I2C_SLAVE_STOP:
> i2c_slave_event(slave, I2C_SLAVE_STOP, &value);
> @@ -335,6 +404,8 @@ static void aspeed_i2c_do_start(struct aspeed_i2c_bus *bus)
> u32 command = ASPEED_I2CD_M_START_CMD | ASPEED_I2CD_M_TX_CMD;
> struct i2c_msg *msg = &bus->msgs[bus->msgs_index];
> u8 slave_addr = i2c_8bit_addr_from_msg(msg);
> + u8 wbuf[4];
> + int len;
>
> #if IS_ENABLED(CONFIG_I2C_SLAVE)
> /*
> @@ -353,12 +424,66 @@ static void aspeed_i2c_do_start(struct aspeed_i2c_bus *bus)
>
> if (msg->flags & I2C_M_RD) {
> command |= ASPEED_I2CD_M_RX_CMD;
> - /* Need to let the hardware know to NACK after RX. */
> - if (msg->len == 1 && !(msg->flags & I2C_M_RECV_LEN))
> - command |= ASPEED_I2CD_M_S_RX_CMD_LAST;
> +
> + if (bus->buf_base && !(msg->flags & I2C_M_RECV_LEN)) {
> + command |= ASPEED_I2CD_RX_BUFF_ENABLE;
> +
> + if (msg->len > bus->buf_size) {
> + len = bus->buf_size;
> + } else {
> + len = msg->len;
> + command |= ASPEED_I2CD_M_S_RX_CMD_LAST;
> + }
> +
> + writel(FIELD_PREP(ASPEED_I2CD_BUF_RX_SIZE_MASK,
> + len - 1) |
> + FIELD_PREP(ASPEED_I2CD_BUF_OFFSET_MASK,
> + bus->buf_offset),
> + bus->base + ASPEED_I2C_BUF_CTRL_REG);
> + } else {
> + /* Need to let the hardware know to NACK after RX. */
> + if (msg->len == 1 && !(msg->flags & I2C_M_RECV_LEN))
> + command |= ASPEED_I2CD_M_S_RX_CMD_LAST;
> + }
> + } else {
> + if (bus->buf_base) {
> + int i;
> +
> + command |= ASPEED_I2CD_TX_BUFF_ENABLE;
> +
> + if (msg->len + 1 > bus->buf_size)
> + len = bus->buf_size;
> + else
> + len = msg->len + 1;
> +
> + /*
> + * Yeah, it looks clumsy but byte writings on a remapped
> + * I2C SRAM cause corruptions so use this way to make
> + * dword writings.
> + */
> + wbuf[0] = slave_addr;
> + for (i = 1; i < len; i++) {
> + wbuf[i % 4] = msg->buf[i - 1];
> + 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_index = len - 1;
> +
> + 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(slave_addr, bus->base + ASPEED_I2C_BYTE_BUF_REG);
> + if (!(command & ASPEED_I2CD_TX_BUFF_ENABLE))
> + writel(slave_addr, bus->base + ASPEED_I2C_BYTE_BUF_REG);
> writel(command, bus->base + ASPEED_I2C_CMD_REG);
> }
>
> @@ -398,7 +523,7 @@ static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
> u32 irq_handled = 0, command = 0;
> struct i2c_msg *msg;
> u8 recv_byte;
> - int ret;
> + int ret, len;
>
> if (irq_status & ASPEED_I2CD_INTR_BUS_RECOVER_DONE) {
> bus->master_state = ASPEED_I2C_MASTER_INACTIVE;
> @@ -511,11 +636,43 @@ static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
> /* fall through */
> case ASPEED_I2C_MASTER_TX_FIRST:
> if (bus->buf_index < msg->len) {
> + command = ASPEED_I2CD_M_TX_CMD;
> +
> + if (bus->buf_base) {
> + 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;
> +
> + 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 - (i % 4));
> +
> + bus->buf_index += len;
> +
> + 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);
> + } else {
> + writel(msg->buf[bus->buf_index++],
> + bus->base + ASPEED_I2C_BYTE_BUF_REG);
> + }
> + writel(command, bus->base + ASPEED_I2C_CMD_REG);
> bus->master_state = ASPEED_I2C_MASTER_TX;
> - writel(msg->buf[bus->buf_index++],
> - bus->base + ASPEED_I2C_BYTE_BUF_REG);
> - writel(ASPEED_I2CD_M_TX_CMD,
> - bus->base + ASPEED_I2C_CMD_REG);
> } else {
> aspeed_i2c_next_msg_or_stop(bus);
> }
> @@ -532,25 +689,56 @@ static u32 aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus, u32 irq_status)
> }
> irq_handled |= ASPEED_I2CD_INTR_RX_DONE;
>
> - recv_byte = readl(bus->base + ASPEED_I2C_BYTE_BUF_REG) >> 8;
> - msg->buf[bus->buf_index++] = recv_byte;
> -
> - if (msg->flags & I2C_M_RECV_LEN) {
> - if (unlikely(recv_byte > I2C_SMBUS_BLOCK_MAX)) {
> - bus->cmd_err = -EPROTO;
> - aspeed_i2c_do_stop(bus);
> - goto out_no_complete;
> + if (bus->buf_base && !(msg->flags & I2C_M_RECV_LEN)) {
> + 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);
> + bus->buf_index += len;
> + } else {
> + recv_byte = readl(bus->base + ASPEED_I2C_BYTE_BUF_REG)
> + >> 8;
> + msg->buf[bus->buf_index++] = recv_byte;
> +
> + if (msg->flags & I2C_M_RECV_LEN) {
> + if (unlikely(recv_byte > I2C_SMBUS_BLOCK_MAX)) {
> + bus->cmd_err = -EPROTO;
> + aspeed_i2c_do_stop(bus);
> + goto out_no_complete;
> + }
> + msg->len = recv_byte +
> + ((msg->flags & I2C_CLIENT_PEC) ?
> + 2 : 1);
> + msg->flags &= ~I2C_M_RECV_LEN;
> }
> - msg->len = recv_byte +
> - ((msg->flags & I2C_CLIENT_PEC) ? 2 : 1);
> - msg->flags &= ~I2C_M_RECV_LEN;
> }
>
> if (bus->buf_index < msg->len) {
> - bus->master_state = ASPEED_I2C_MASTER_RX;
> command = ASPEED_I2CD_M_RX_CMD;
> - if (bus->buf_index + 1 == msg->len)
> - command |= ASPEED_I2CD_M_S_RX_CMD_LAST;
> + bus->master_state = ASPEED_I2C_MASTER_RX;
> + if (bus->buf_base) {
> + command |= ASPEED_I2CD_RX_BUFF_ENABLE;
> +
> + if (msg->len - bus->buf_index >
> + bus->buf_size) {
> + len = bus->buf_size;
> + } else {
> + len = msg->len - bus->buf_index;
> + command |= ASPEED_I2CD_M_S_RX_CMD_LAST;
> + }
> +
> + 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;
> + }
> writel(command, bus->base + ASPEED_I2C_CMD_REG);
> } else {
> aspeed_i2c_next_msg_or_stop(bus);
> @@ -890,6 +1078,9 @@ static int aspeed_i2c_init(struct aspeed_i2c_bus *bus,
> if (ret < 0)
> return ret;
>
> + fun_ctrl_reg |= FIELD_PREP(ASPEED_I2CD_BUFFER_PAGE_SEL_MASK,
> + bus->buf_page);
> +
> if (of_property_read_bool(pdev->dev.of_node, "multi-master"))
> bus->multi_master = true;
> else
> @@ -947,16 +1138,15 @@ static int aspeed_i2c_probe_bus(struct platform_device *pdev)
> {
> const struct of_device_id *match;
> struct aspeed_i2c_bus *bus;
> + bool sram_enabled = true;
> struct clk *parent_clk;
> - struct resource *res;
> int irq, ret;
>
> bus = devm_kzalloc(&pdev->dev, sizeof(*bus), GFP_KERNEL);
> if (!bus)
> return -ENOMEM;
>
> - res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> - bus->base = devm_ioremap_resource(&pdev->dev, res);
> + bus->base = devm_platform_ioremap_resource(pdev, 0);
> if (IS_ERR(bus->base))
> return PTR_ERR(bus->base);
>
> @@ -990,6 +1180,45 @@ static int aspeed_i2c_probe_bus(struct platform_device *pdev)
> bus->get_clk_reg_val = (u32 (*)(struct device *, u32))
> match->data;
>
> + /*
> + * Enable I2C SRAM in case of AST2500.
> + * SRAM is enabled by default in AST2400 and AST2600.
> + */
This probe function is already pretty complicated as it is. Can we move
this to a helper function (especially since it only applies to the
25xx)?
> + if (of_device_is_compatible(pdev->dev.of_node,
> + "aspeed,ast2500-i2c-bus")) {
> + struct regmap *gr_regmap = syscon_regmap_lookup_by_compatible("aspeed,ast2500-i2c-gr");
So this memory is global, right? It is shared by all the busses?
If I am reading this right, then I think we need to protect so that only
one bus is accessing this memory at a time.
> + if (IS_ERR(gr_regmap))
> + ret = PTR_ERR(gr_regmap);
> + else
> + ret = regmap_update_bits(gr_regmap,
> + ASPEED_I2CG_GLOBAL_CTRL_REG,
> + ASPEED_I2CG_SRAM_BUFFER_EN,
> + ASPEED_I2CG_SRAM_BUFFER_EN);
> +
> + if (ret)
> + sram_enabled = false;
> + }
> +
> + if (sram_enabled) {
> + struct resource *res = platform_get_resource(pdev,
> + IORESOURCE_MEM, 1);
> +
> + if (res && resource_size(res) >= 2)
> + bus->buf_base = devm_ioremap_resource(&pdev->dev, res);
> +
> + if (!IS_ERR_OR_NULL(bus->buf_base)) {
> + bus->buf_size = resource_size(res);
> + if (of_device_is_compatible(pdev->dev.of_node,
> + "aspeed,ast2400-i2c-bus")) {
> + bus->buf_page = ((res->start >> 8) &
> + GENMASK(3, 0)) - 8;
> + bus->buf_offset = (res->start >> 2) &
> + ASPEED_I2CD_BUF_OFFSET_MASK;
> + }
> + }
> + }
> +
> /* Initialize the I2C adapter */
> spin_lock_init(&bus->lock);
> init_completion(&bus->cmd_complete);
> @@ -1026,8 +1255,8 @@ static int aspeed_i2c_probe_bus(struct platform_device *pdev)
>
> platform_set_drvdata(pdev, bus);
>
> - dev_info(bus->dev, "i2c bus %d registered, irq %d\n",
> - bus->adap.nr, irq);
> + dev_info(bus->dev, "i2c bus %d registered (%s mode), irq %d\n",
> + bus->adap.nr, bus->buf_base ? "buffer" : "byte", irq);
>
> return 0;
> }
> --
> 2.23.0
>
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