Re: [PATCH v4 1/2] i2c: aspeed: added driver for Aspeed I2C

[Kachalov Anton <mouse-Pma6HLj0uuo@public.gmane.org>]

Hello.

I would like to add my five cents here. Do not limit the bus_clk with 400kHz (FM) while HighSpeed is above 1MHz (above FM+ devices). I've successfully tested FM+ (1Mhz) in a quite big i2c network (a number of pca9600, pca9675, pca9848) with at least eight AST2150 SoCs on the common bus.

BTW. Just a lame question. If the device isn't designed to work on the higher speed (like standard of FM) while the bus selected as FM+, would those kind of devices just unoperate or may have undefined behavior and disturb the SDA/SCL? Just wondering to dynamically slowdown down to 100Khz (if needed) for the specific slave, but keep high rate (FM+) at the normal operation.

--- source/drivers/i2c/busses/i2c-aspeed.c.orig	2016-11-18 19:17:41.000000000 +0300
+++ source/drivers/i2c/busses/i2c-aspeed.c	2016-11-18 19:17:49.682092658 +0300
@@ -310,7 +310,7 @@ static void ast_i2c_dev_init(struct ast_
 			bus->bus_clk, clk_get_rate(bus->pclk));
 
 	/* Set AC Timing */
-	if(bus->bus_clk / 1000 > 400) {
+	if(bus->bus_clk / 1000 > 1000) {
 		ast_i2c_write(bus, ast_i2c_read(bus, I2C_FUN_CTRL_REG) |
 				AST_I2CD_M_HIGH_SPEED_EN |
 				AST_I2CD_M_SDA_DRIVE_1T_EN |

22.11.2016, 12:07, "Cédric Le Goater" <clg-Bxea+6Xhats@public.gmane.org>:
> Hello Brendan,
>
> A few comments below,
>
> On 11/05/2016 02:58 AM, Brendan Higgins wrote:
>>  Added initial master and slave support for Aspeed I2C controller.
>>  Supports fourteen busses present in ast24xx and ast25xx BMC SoCs by
>>  Aspeed.
>>
>>  Signed-off-by: Brendan Higgins <brendanhiggins-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
>>  ---
>>  Changes for v2:
>>    - Added single module_init (multiple was breaking some builds).
>>  Changes for v3:
>>    - Removed "bus" device tree param; now extracted from bus address offset
>>  Changes for v4:
>>    - I2C adapter number is now generated dynamically unless specified in alias.
>>  ---
>>   drivers/i2c/busses/Kconfig | 10 +
>>   drivers/i2c/busses/Makefile | 1 +
>>   drivers/i2c/busses/i2c-aspeed.c | 807 ++++++++++++++++++++++++++++++++++++++++
>>   3 files changed, 818 insertions(+)
>>   create mode 100644 drivers/i2c/busses/i2c-aspeed.c
>>
>>  diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
>>  index d252276..b6caa5d 100644
>>  --- a/drivers/i2c/busses/Kconfig
>>  +++ b/drivers/i2c/busses/Kconfig
>>  @@ -1009,6 +1009,16 @@ config I2C_RCAR
>>             This driver can also be built as a module. If so, the module
>>             will be called i2c-rcar.
>>
>>  +config I2C_ASPEED
>>  + tristate "Aspeed AST2xxx SoC I2C Controller"
>>  + depends on ARCH_ASPEED
>>  + help
>>  + If you say yes to this option, support will be included for the
>>  + Aspeed AST2xxx SoC I2C controller.
>>  +
>>  + This driver can also be built as a module. If so, the module
>>  + will be called i2c-aspeed.
>>  +
>>   comment "External I2C/SMBus adapter drivers"
>>
>>   config I2C_DIOLAN_U2C
>>  diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
>>  index 29764cc..826e780 100644
>>  --- a/drivers/i2c/busses/Makefile
>>  +++ b/drivers/i2c/busses/Makefile
>>  @@ -99,6 +99,7 @@ obj-$(CONFIG_I2C_XILINX) += i2c-xiic.o
>>   obj-$(CONFIG_I2C_XLR) += i2c-xlr.o
>>   obj-$(CONFIG_I2C_XLP9XX) += i2c-xlp9xx.o
>>   obj-$(CONFIG_I2C_RCAR) += i2c-rcar.o
>>  +obj-$(CONFIG_I2C_ASPEED) += i2c-aspeed.o
>>
>>   # External I2C/SMBus adapter drivers
>>   obj-$(CONFIG_I2C_DIOLAN_U2C) += i2c-diolan-u2c.o
>>  diff --git a/drivers/i2c/busses/i2c-aspeed.c b/drivers/i2c/busses/i2c-aspeed.c
>>  new file mode 100644
>>  index 0000000..88e078a
>>  --- /dev/null
>>  +++ b/drivers/i2c/busses/i2c-aspeed.c
>>  @@ -0,0 +1,807 @@
>>  +/*
>>  + * I2C adapter for the ASPEED I2C bus.
>>  + *
>>  + * Copyright (C) 2012-2020 ASPEED Technology Inc.
>>  + * Copyright 2016 IBM Corporation
>>  + * Copyright 2016 Google, Inc.
>>  + *
>>  + * This program is free software; you can redistribute it and/or modify
>>  + * it under the terms of the GNU General Public License version 2 as
>>  + * published by the Free Software Foundation.
>>  + */
>>  +
>>  +#include <linux/kernel.h>
>>  +#include <linux/module.h>
>>  +#include <linux/i2c.h>
>>  +#include <linux/irq.h>
>>  +#include <linux/irqdomain.h>
>>  +#include <linux/init.h>
>>  +#include <linux/io.h>
>>  +#include <linux/errno.h>
>>  +#include <linux/interrupt.h>
>>  +#include <linux/completion.h>
>>  +#include <linux/slab.h>
>>  +#include <linux/of_address.h>
>>  +#include <linux/of_platform.h>
>>  +#include <linux/platform_device.h>
>>  +#include <linux/err.h>
>>  +#include <linux/clk.h>
>>  +
>>  +/* I2C Register */
>>  +#define ASPEED_I2C_FUN_CTRL_REG 0x00
>>  +#define ASPEED_I2C_AC_TIMING_REG1 0x04
>>  +#define ASPEED_I2C_AC_TIMING_REG2 0x08
>>  +#define ASPEED_I2C_INTR_CTRL_REG 0x0c
>>  +#define ASPEED_I2C_INTR_STS_REG 0x10
>>  +#define ASPEED_I2C_CMD_REG 0x14
>>  +#define ASPEED_I2C_DEV_ADDR_REG 0x18
>>  +#define ASPEED_I2C_BYTE_BUF_REG 0x20
>>  +#define ASPEED_I2C_OFFSET_START 0x40
>>  +#define ASPEED_I2C_OFFSET_INCREMENT 0x40
>>  +
>>  +#define ASPEED_I2C_NUM_BUS 14
>>  +
>>  +/* Global Register Definition */
>>  +/* 0x00 : I2C Interrupt Status Register */
>>  +/* 0x08 : I2C Interrupt Target Assignment */
>>  +
>>  +/* Device Register Definition */
>>  +/* 0x00 : I2CD Function Control Register */
>>  +#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)
>>  +#define ASPEED_I2CD_M_HIGH_SPEED_EN BIT(6)
>>  +#define ASPEED_I2CD_SLAVE_EN BIT(1)
>>  +#define ASPEED_I2CD_MASTER_EN BIT(0)
>>  +
>>  +/* 0x08 : I2CD Clock and AC Timing Control Register #2 */
>>  +#define ASPEED_NO_TIMEOUT_CTRL 0
>>  +
>>  +
>>  +/* 0x0c : I2CD Interrupt Control Register &
>>  + * 0x10 : I2CD Interrupt Status Register
>>  + *
>>  + * These share bit definitions, so use the same values for the enable &
>>  + * status bits.
>>  + */
>>  +#define ASPEED_I2CD_INTR_SDA_DL_TIMEOUT BIT(14)
>>  +#define ASPEED_I2CD_INTR_BUS_RECOVER_DONE BIT(13)
>>  +#define ASPEED_I2CD_INTR_SLAVE_MATCH BIT(7)
>>  +#define ASPEED_I2CD_INTR_SCL_TIMEOUT BIT(6)
>>  +#define ASPEED_I2CD_INTR_ABNORMAL BIT(5)
>>  +#define ASPEED_I2CD_INTR_NORMAL_STOP BIT(4)
>>  +#define ASPEED_I2CD_INTR_ARBIT_LOSS BIT(3)
>>  +#define ASPEED_I2CD_INTR_RX_DONE BIT(2)
>>  +#define ASPEED_I2CD_INTR_TX_NAK BIT(1)
>>  +#define ASPEED_I2CD_INTR_TX_ACK BIT(0)
>>  +
>>  +/* 0x14 : I2CD Command/Status Register */
>>  +#define ASPEED_I2CD_SCL_LINE_STS BIT(18)
>>  +#define ASPEED_I2CD_SDA_LINE_STS BIT(17)
>>  +#define ASPEED_I2CD_BUS_BUSY_STS BIT(16)
>>  +#define ASPEED_I2CD_BUS_RECOVER_CMD BIT(11)
>>  +
>>  +/* Command Bit */
>>  +#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)
>>  +#define ASPEED_I2CD_S_TX_CMD BIT(2)
>>  +#define ASPEED_I2CD_M_TX_CMD BIT(1)
>>  +#define ASPEED_I2CD_M_START_CMD BIT(0)
>>  +
>>  +/* 0x18 : I2CD Slave Device Address Register */
>>  +#define ASPEED_I2CD_DEV_ADDR_MASK GENMASK(6, 0)
>>  +
>>  +enum aspeed_i2c_slave_state {
>>  + ASPEED_I2C_SLAVE_START,
>>  + ASPEED_I2C_SLAVE_READ_REQUESTED,
>>  + ASPEED_I2C_SLAVE_READ_PROCESSED,
>>  + ASPEED_I2C_SLAVE_WRITE_REQUESTED,
>>  + ASPEED_I2C_SLAVE_WRITE_RECEIVED,
>>  + ASPEED_I2C_SLAVE_STOP,
>>  +};
>>  +
>>  +struct aspeed_i2c_bus {
>>  + struct i2c_adapter adap;
>>  + struct device *dev;
>>  + void __iomem *base;
>>  + spinlock_t lock;
>>  + struct completion cmd_complete;
>>  + int irq;
>>  + /* Transaction state. */
>>  + struct i2c_msg *msg;
>>  + int msg_pos;
>>  + u32 cmd_err;
>>  +#if IS_ENABLED(CONFIG_I2C_SLAVE)
>>  + struct i2c_client *slave;
>>  + enum aspeed_i2c_slave_state slave_state;
>>  +#endif
>>  +};
>>  +
>>  +struct aspeed_i2c_controller {
>>  + struct device *dev;
>>  + void __iomem *base;
>>  + int irq;
>>  + struct irq_domain *irq_domain;
>>  +};
>>  +
>>  +static inline void aspeed_i2c_write(struct aspeed_i2c_bus *bus, u32 val,
>>  + u32 reg)
>>  +{
>>  + writel(val, bus->base + reg);
>>  +}
>>  +
>>  +static inline u32 aspeed_i2c_read(struct aspeed_i2c_bus *bus, u32 reg)
>>  +{
>>  + return readl(bus->base + reg);
>>  +}
>>  +
>>  +static u8 aspeed_i2c_recover_bus(struct aspeed_i2c_bus *bus)
>>  +{
>>  + u32 command;
>>  + unsigned long time_left;
>>  + unsigned long flags;
>>  + int ret = 0;
>>  +
>>  + spin_lock_irqsave(&bus->lock, flags);
>>  + command = aspeed_i2c_read(bus, ASPEED_I2C_CMD_REG);
>>  + /* Bus is idle: no recovery needed. */
>>  + if ((command & ASPEED_I2CD_SDA_LINE_STS) &&
>>  + (command & ASPEED_I2CD_SCL_LINE_STS))
>>  + goto out;
>>  +
>>  + dev_dbg(bus->dev, "bus hung (state %x), attempting recovery\n",
>>  + command);
>>  +
>>  + /* Bus held: put bus in stop state. */
>>  + if ((command & ASPEED_I2CD_SDA_LINE_STS) &&
>>  + !(command & ASPEED_I2CD_SCL_LINE_STS)) {
>>  + aspeed_i2c_write(bus, ASPEED_I2CD_M_STOP_CMD,
>>  + ASPEED_I2C_CMD_REG);
>>  + reinit_completion(&bus->cmd_complete);
>>  + spin_unlock_irqrestore(&bus->lock, flags);
>>  +
>>  + time_left = wait_for_completion_interruptible_timeout(
>>  + &bus->cmd_complete, bus->adap.timeout * HZ);
>>  +
>>  + spin_lock_irqsave(&bus->lock, flags);
>>  + if (time_left == 0)
>>  + ret = -ETIMEDOUT;
>>  + else if (bus->cmd_err)
>>  + ret = -EIO;
>>  + /* Bus error. */
>>  + } else if (!(command & ASPEED_I2CD_SDA_LINE_STS)) {
>>  + aspeed_i2c_write(bus, ASPEED_I2CD_BUS_RECOVER_CMD,
>>  + ASPEED_I2C_CMD_REG);
>>  + reinit_completion(&bus->cmd_complete);
>>  + spin_unlock_irqrestore(&bus->lock, flags);
>>  +
>>  + time_left = wait_for_completion_interruptible_timeout(
>>  + &bus->cmd_complete, bus->adap.timeout * HZ);
>>  +
>>  + spin_lock_irqsave(&bus->lock, flags);
>>  + if (time_left == 0)
>>  + ret = -ETIMEDOUT;
>>  + else if (bus->cmd_err)
>>  + ret = -EIO;
>>  + /* Recovery failed. */
>>  + else if (!(aspeed_i2c_read(bus, ASPEED_I2C_CMD_REG) &
>>  + ASPEED_I2CD_SDA_LINE_STS))
>>  + ret = -EIO;
>>  + }
>>  +
>>  +out:
>>  + spin_unlock_irqrestore(&bus->lock, flags);
>>  + return ret;
>>  +}
>>  +
>>  +#if IS_ENABLED(CONFIG_I2C_SLAVE)
>>  +static bool aspeed_i2c_slave_irq(struct aspeed_i2c_bus *bus)
>>  +{
>>  + bool irq_handled = true;
>>  + u32 command;
>>  + u32 irq_status;
>>  + u32 status_ack = 0;
>>  + u8 value;
>>  + struct i2c_client *slave = bus->slave;
>>  +
>>  + spin_lock(&bus->lock);
>>  + if (!slave) {
>>  + irq_handled = false;
>>  + goto out;
>>  + }
>>  + command = aspeed_i2c_read(bus, ASPEED_I2C_CMD_REG);
>>  + irq_status = aspeed_i2c_read(bus, ASPEED_I2C_INTR_STS_REG);
>>  +
>>  + /* Slave was requested, restart state machine. */
>>  + if (irq_status & ASPEED_I2CD_INTR_SLAVE_MATCH) {
>>  + status_ack |= ASPEED_I2CD_INTR_SLAVE_MATCH;
>>  + bus->slave_state = ASPEED_I2C_SLAVE_START;
>>  + }
>>  + /* Slave is not currently active, irq was for someone else. */
>>  + if (bus->slave_state == ASPEED_I2C_SLAVE_STOP) {
>>  + irq_handled = false;
>>  + goto out;
>>  + }
>>  +
>>  + dev_dbg(bus->dev, "slave irq status 0x%08x, cmd 0x%08x\n",
>>  + irq_status, command);
>>  +
>>  + /* Slave was sent something. */
>>  + if (irq_status & ASPEED_I2CD_INTR_RX_DONE) {
>>  + value = aspeed_i2c_read(bus, ASPEED_I2C_BYTE_BUF_REG) >> 8;
>>  + /* Handle address frame. */
>>  + if (bus->slave_state == ASPEED_I2C_SLAVE_START) {
>>  + if (value & 0x1)
>>  + bus->slave_state =
>>  + ASPEED_I2C_SLAVE_READ_REQUESTED;
>>  + else
>>  + bus->slave_state =
>>  + ASPEED_I2C_SLAVE_WRITE_REQUESTED;
>>  + }
>>  + status_ack |= ASPEED_I2CD_INTR_RX_DONE;
>>  + }
>>  +
>>  + /* Slave was asked to stop. */
>>  + if (irq_status & ASPEED_I2CD_INTR_NORMAL_STOP) {
>>  + status_ack |= ASPEED_I2CD_INTR_NORMAL_STOP;
>>  + bus->slave_state = ASPEED_I2C_SLAVE_STOP;
>>  + }
>>  + if (irq_status & ASPEED_I2CD_INTR_TX_NAK) {
>>  + status_ack |= ASPEED_I2CD_INTR_TX_NAK;
>>  + bus->slave_state = ASPEED_I2C_SLAVE_STOP;
>>  + }
>>  +
>>  + if (bus->slave_state == ASPEED_I2C_SLAVE_READ_REQUESTED) {
>>  + if (irq_status & ASPEED_I2CD_INTR_TX_ACK)
>>  + dev_err(bus->dev, "Unexpected ACK on read request.\n");
>>  + bus->slave_state = ASPEED_I2C_SLAVE_READ_PROCESSED;
>>  +
>>  + i2c_slave_event(slave, I2C_SLAVE_READ_REQUESTED, &value);
>>  + aspeed_i2c_write(bus, value, ASPEED_I2C_BYTE_BUF_REG);
>>  + aspeed_i2c_write(bus, ASPEED_I2CD_S_TX_CMD, ASPEED_I2C_CMD_REG);
>>  + } else if (bus->slave_state == ASPEED_I2C_SLAVE_READ_PROCESSED) {
>>  + status_ack |= ASPEED_I2CD_INTR_TX_ACK;
>>  + if (!(irq_status & ASPEED_I2CD_INTR_TX_ACK))
>>  + dev_err(bus->dev,
>>  + "Expected ACK after processed read.\n");
>>  + i2c_slave_event(slave, I2C_SLAVE_READ_PROCESSED, &value);
>>  + aspeed_i2c_write(bus, value, ASPEED_I2C_BYTE_BUF_REG);
>>  + aspeed_i2c_write(bus, ASPEED_I2CD_S_TX_CMD, ASPEED_I2C_CMD_REG);
>>  + } else if (bus->slave_state == ASPEED_I2C_SLAVE_WRITE_REQUESTED) {
>>  + bus->slave_state = ASPEED_I2C_SLAVE_WRITE_RECEIVED;
>>  + i2c_slave_event(slave, I2C_SLAVE_WRITE_REQUESTED, &value);
>>  + } else if (bus->slave_state == ASPEED_I2C_SLAVE_WRITE_RECEIVED) {
>>  + i2c_slave_event(slave, I2C_SLAVE_WRITE_RECEIVED, &value);
>>  + } else if (bus->slave_state == ASPEED_I2C_SLAVE_STOP) {
>>  + i2c_slave_event(slave, I2C_SLAVE_STOP, &value);
>>  + }
>>  +
>>  + if (status_ack != irq_status)
>>  + dev_err(bus->dev,
>>  + "irq handled != irq. expected %x, but was %x\n",
>>  + irq_status, status_ack);
>>  + aspeed_i2c_write(bus, status_ack, ASPEED_I2C_INTR_STS_REG);
>>  +
>>  +out:
>>  + spin_unlock(&bus->lock);
>>  + return irq_handled;
>>  +}
>>  +#endif
>>  +
>>  +static bool aspeed_i2c_master_irq(struct aspeed_i2c_bus *bus)
>>  +{
>>  + const u32 errs = ASPEED_I2CD_INTR_ARBIT_LOSS |
>>  + ASPEED_I2CD_INTR_ABNORMAL |
>>  + ASPEED_I2CD_INTR_SCL_TIMEOUT |
>>  + ASPEED_I2CD_INTR_SDA_DL_TIMEOUT |
>>  + ASPEED_I2CD_INTR_TX_NAK;
>>  + u32 irq_status;
>>  +
>>  + spin_lock(&bus->lock);
>>  + irq_status = aspeed_i2c_read(bus, ASPEED_I2C_INTR_STS_REG);
>>  + bus->cmd_err = irq_status & errs;
>>  +
>>  + dev_dbg(bus->dev, "master irq status 0x%08x\n", irq_status);
>>  +
>>  + /* No message to transfer. */
>>  + if (bus->cmd_err ||
>>  + (irq_status & ASPEED_I2CD_INTR_NORMAL_STOP) ||
>>  + (irq_status & ASPEED_I2CD_INTR_BUS_RECOVER_DONE)) {
>>  + complete(&bus->cmd_complete);
>>  + goto out;
>>  + } else if (!bus->msg || bus->msg_pos >= bus->msg->len)
>>  + goto out;
>>  +
>>  + if ((bus->msg->flags & I2C_M_RD) &&
>>  + (irq_status & ASPEED_I2CD_INTR_RX_DONE)) {
>>  + bus->msg->buf[bus->msg_pos++] = aspeed_i2c_read(
>>  + bus, ASPEED_I2C_BYTE_BUF_REG) >> 8;
>>  + if (bus->msg_pos + 1 < bus->msg->len)
>>  + aspeed_i2c_write(bus, ASPEED_I2CD_M_RX_CMD,
>>  + ASPEED_I2C_CMD_REG);
>>  + else if (bus->msg_pos < bus->msg->len)
>>  + aspeed_i2c_write(bus, ASPEED_I2CD_M_RX_CMD |
>>  + ASPEED_I2CD_M_S_RX_CMD_LAST,
>>  + ASPEED_I2C_CMD_REG);
>>  + } else if (!(bus->msg->flags & I2C_M_RD) &&
>>  + (irq_status & ASPEED_I2CD_INTR_TX_ACK)) {
>>  + aspeed_i2c_write(bus, bus->msg->buf[bus->msg_pos++],
>>  + ASPEED_I2C_BYTE_BUF_REG);
>>  + aspeed_i2c_write(bus, ASPEED_I2CD_M_TX_CMD, ASPEED_I2C_CMD_REG);
>>  + }
>
> is it safe to start a new transaction when in a interrupt handler ?
>
>>  + /* Transmission complete: notify caller. */
>>  + if (bus->msg_pos >= bus->msg->len)
>>  + complete(&bus->cmd_complete);
>>  +out:
>>  + aspeed_i2c_write(bus, irq_status, ASPEED_I2C_INTR_STS_REG);
>
> so this is clearing the interrupt status just after having started
> a new transaction on the bus. It looks unsafe to me as it could
> clear the status of the just started transaction.
>
>>  + spin_unlock(&bus->lock);
>>  + return true;
>>  +}
>>  +
>>  +static irqreturn_t aspeed_i2c_bus_irq(int irq, void *dev_id)
>>  +{
>>  + struct aspeed_i2c_bus *bus = dev_id;
>>  +
>>  +#if IS_ENABLED(CONFIG_I2C_SLAVE)
>>  + if (aspeed_i2c_slave_irq(bus)) {
>>  + dev_dbg(bus->dev, "irq handled by slave.\n");
>>  + return IRQ_HANDLED;
>>  + }
>>  +#endif
>>  + if (aspeed_i2c_master_irq(bus)) {
>>  + dev_dbg(bus->dev, "irq handled by master.\n");
>>  + return IRQ_HANDLED;
>>  + }
>>  + dev_err(bus->dev, "irq not handled properly!\n");
>>  + return IRQ_HANDLED;
>>  +}
>>  +
>>  +static int aspeed_i2c_master_single_xfer(struct i2c_adapter *adap,
>>  + struct i2c_msg *msg)
>>  +{
>>  + struct aspeed_i2c_bus *bus = adap->algo_data;
>>  + unsigned long flags;
>>  + u8 slave_addr;
>>  + u32 command = ASPEED_I2CD_M_START_CMD | ASPEED_I2CD_M_TX_CMD;
>>  + int ret = msg->len;
>>  + unsigned long time_left;
>>  +
>>  + spin_lock_irqsave(&bus->lock, flags);
>>  + bus->msg = msg;
>>  + bus->msg_pos = 0;
>>  + slave_addr = msg->addr << 1;
>>  + if (msg->flags & I2C_M_RD) {
>>  + slave_addr |= 1;
>>  + command |= ASPEED_I2CD_M_RX_CMD;
>>  + if (msg->len == 1)
>>  + command |= ASPEED_I2CD_M_S_RX_CMD_LAST;
>>  + }
>>  + aspeed_i2c_write(bus, slave_addr, ASPEED_I2C_BYTE_BUF_REG);
>>  + aspeed_i2c_write(bus, command, ASPEED_I2C_CMD_REG);
>>  + reinit_completion(&bus->cmd_complete);
>>  + spin_unlock_irqrestore(&bus->lock, flags);
>>  +
>>  + time_left = wait_for_completion_interruptible_timeout(
>>  + &bus->cmd_complete, bus->adap.timeout * HZ * msg->len);
>
> Why do you multiply by * msg->len ?
>
>>  + if (time_left == 0)
>>  + return -ETIMEDOUT;
>>  +
>>  + spin_lock_irqsave(&bus->lock, flags);
>>  + if (bus->cmd_err)
>>  + ret = -EIO;
>>  + bus->msg = NULL;
>>  + spin_unlock_irqrestore(&bus->lock, flags);
>>  +
>>  + return ret;
>>  +}
>>  +
>>  +static int aspeed_i2c_master_xfer(struct i2c_adapter *adap,
>>  + struct i2c_msg *msgs, int num)
>>  +{
>>  + struct aspeed_i2c_bus *bus = adap->algo_data;
>>  + int ret;
>>  + int i;
>>  + unsigned long flags;
>>  + unsigned long time_left;
>>  +
>>  + /* If bus is busy, attempt recovery. We assume a single master
>>  + * environment.
>>  + */
>>  + if (aspeed_i2c_read(bus, ASPEED_I2C_CMD_REG) &
>>  + ASPEED_I2CD_BUS_BUSY_STS) {
>>  + ret = aspeed_i2c_recover_bus(bus);
>>  + if (ret)
>>  + return ret;
>>  + }
>>  +
>>  + for (i = 0; i < num; i++) {
>>  + ret = aspeed_i2c_master_single_xfer(adap, &msgs[i]);
>>  + if (ret < 0)
>>  + break;
>>  + /* TODO: Support other forms of I2C protocol mangling. */
>>  + if (msgs[i].flags & I2C_M_STOP) {
>>  + spin_lock_irqsave(&bus->lock, flags);
>>  + aspeed_i2c_write(bus, ASPEED_I2CD_M_STOP_CMD,
>>  + ASPEED_I2C_CMD_REG);
>>  + reinit_completion(&bus->cmd_complete);
>>  + spin_unlock_irqrestore(&bus->lock, flags);
>>  +
>>  + time_left = wait_for_completion_interruptible_timeout(
>>  + &bus->cmd_complete,
>>  + bus->adap.timeout * HZ);
>>  + if (time_left == 0)
>>  + return -ETIMEDOUT;
>>  + }
>>  + }
>>  +
>>  + spin_lock_irqsave(&bus->lock, flags);
>>  + aspeed_i2c_write(bus, ASPEED_I2CD_M_STOP_CMD, ASPEED_I2C_CMD_REG);
>>  + reinit_completion(&bus->cmd_complete);
>>  + spin_unlock_irqrestore(&bus->lock, flags);
>>  +
>>  + time_left = wait_for_completion_interruptible_timeout(
>>  + &bus->cmd_complete, bus->adap.timeout * HZ);
>>  + if (time_left == 0)
>>  + return -ETIMEDOUT;
>>  +
>>  + /* If nothing went wrong, return number of messages transferred. */
>>  + if (ret < 0)
>>  + return ret;
>>  + else
>>  + return i;
>>  +}
>>  +
>>  +static u32 aspeed_i2c_functionality(struct i2c_adapter *adap)
>>  +{
>>  + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA;
>>  +}
>>  +
>>  +#if IS_ENABLED(CONFIG_I2C_SLAVE)
>>  +static int aspeed_i2c_reg_slave(struct i2c_client *client)
>>  +{
>>  + struct aspeed_i2c_bus *bus;
>>  + unsigned long flags;
>>  + u32 addr_reg_val;
>>  + u32 func_ctrl_reg_val;
>>  +
>>  + bus = client->adapter->algo_data;
>>  + spin_lock_irqsave(&bus->lock, flags);
>>  + if (bus->slave) {
>>  + spin_unlock_irqrestore(&bus->lock, flags);
>>  + return -EINVAL;
>>  + }
>>  +
>>  + /* Set slave addr. */
>>  + addr_reg_val = aspeed_i2c_read(bus, ASPEED_I2C_DEV_ADDR_REG);
>>  + addr_reg_val &= ~ASPEED_I2CD_DEV_ADDR_MASK;
>>  + addr_reg_val |= client->addr & ASPEED_I2CD_DEV_ADDR_MASK;
>>  + aspeed_i2c_write(bus, addr_reg_val, ASPEED_I2C_DEV_ADDR_REG);
>>  +
>>  + /* Switch from master mode to slave mode. */
>>  + func_ctrl_reg_val = aspeed_i2c_read(bus, ASPEED_I2C_FUN_CTRL_REG);
>>  + func_ctrl_reg_val &= ~ASPEED_I2CD_MASTER_EN;
>>  + func_ctrl_reg_val |= ASPEED_I2CD_SLAVE_EN;
>>  + aspeed_i2c_write(bus, func_ctrl_reg_val, ASPEED_I2C_FUN_CTRL_REG);
>>  +
>>  + bus->slave = client;
>>  + bus->slave_state = ASPEED_I2C_SLAVE_STOP;
>>  + spin_unlock_irqrestore(&bus->lock, flags);
>>  + return 0;
>>  +}
>>  +
>>  +static int aspeed_i2c_unreg_slave(struct i2c_client *client)
>>  +{
>>  + struct aspeed_i2c_bus *bus = client->adapter->algo_data;
>>  + unsigned long flags;
>>  + u32 func_ctrl_reg_val;
>>  +
>>  + spin_lock_irqsave(&bus->lock, flags);
>>  + if (!bus->slave) {
>>  + spin_unlock_irqrestore(&bus->lock, flags);
>>  + return -EINVAL;
>>  + }
>>  +
>>  + /* Switch from slave mode to master mode. */
>>  + func_ctrl_reg_val = aspeed_i2c_read(bus, ASPEED_I2C_FUN_CTRL_REG);
>>  + func_ctrl_reg_val &= ~ASPEED_I2CD_SLAVE_EN;
>>  + func_ctrl_reg_val |= ASPEED_I2CD_MASTER_EN;
>>  + aspeed_i2c_write(bus, func_ctrl_reg_val, ASPEED_I2C_FUN_CTRL_REG);
>>  +
>>  + bus->slave = NULL;
>>  + spin_unlock_irqrestore(&bus->lock, flags);
>>  + return 0;
>>  +}
>>  +#endif
>>  +
>>  +static const struct i2c_algorithm aspeed_i2c_algo = {
>>  + .master_xfer = aspeed_i2c_master_xfer,
>>  + .functionality = aspeed_i2c_functionality,
>>  +#if IS_ENABLED(CONFIG_I2C_SLAVE)
>>  + .reg_slave = aspeed_i2c_reg_slave,
>>  + .unreg_slave = aspeed_i2c_unreg_slave,
>>  +#endif
>>  +};
>>  +
>>  +static u32 aspeed_i2c_get_clk_reg_val(u32 divider_ratio)
>>  +{
>>  + unsigned int inc = 0, div;
>>  + u32 scl_low, scl_high, data;
>>  +
>>  + for (div = 0; divider_ratio >= 16; div++) {
>>  + inc |= (divider_ratio & 1);
>>  + divider_ratio >>= 1;
>>  + }
>>  + divider_ratio += inc;
>>  + scl_low = (divider_ratio >> 1) - 1;
>>  + scl_high = divider_ratio - scl_low - 2;
>>  + data = 0x77700300 | (scl_high << 16) | (scl_low << 12) | div;
>>  + return data;
>>  +}
>>  +
>>  +static int aspeed_i2c_init_clk(struct aspeed_i2c_bus *bus,
>>  + struct platform_device *pdev)
>>  +{
>>  + struct clk *pclk;
>>  + u32 clk_freq;
>>  + u32 divider_ratio;
>>  + int ret;
>>  +
>>  + pclk = devm_clk_get(&pdev->dev, NULL);
>>  + if (IS_ERR(pclk)) {
>>  + dev_err(&pdev->dev, "clk_get failed\n");
>>  + return PTR_ERR(pclk);
>>  + }
>>  + ret = of_property_read_u32(pdev->dev.of_node,
>>  + "clock-frequency", &clk_freq);
>>  + if (ret < 0) {
>>  + dev_err(&pdev->dev,
>>  + "Could not read clock-frequency property\n");
>>  + clk_freq = 100000;
>>  + }
>>  + divider_ratio = clk_get_rate(pclk) / clk_freq;
>>  + /* We just need the clock rate, we don't actually use the clk object. */
>>  + devm_clk_put(&pdev->dev, pclk);
>>  +
>>  + /* Set AC Timing */
>>  + if (clk_freq / 1000 > 400) {
>>  + aspeed_i2c_write(bus, aspeed_i2c_read(bus,
>>  + ASPEED_I2C_FUN_CTRL_REG) |
>>  + ASPEED_I2CD_M_HIGH_SPEED_EN |
>>  + ASPEED_I2CD_M_SDA_DRIVE_1T_EN |
>>  + ASPEED_I2CD_SDA_DRIVE_1T_EN,
>>  + ASPEED_I2C_FUN_CTRL_REG);
>>  +
>>  + aspeed_i2c_write(bus, 0x3, ASPEED_I2C_AC_TIMING_REG2);
>>  + aspeed_i2c_write(bus, aspeed_i2c_get_clk_reg_val(divider_ratio),
>>  + ASPEED_I2C_AC_TIMING_REG1);
>>  + } else {
>>  + aspeed_i2c_write(bus, aspeed_i2c_get_clk_reg_val(divider_ratio),
>>  + ASPEED_I2C_AC_TIMING_REG1);
>>  + aspeed_i2c_write(bus, ASPEED_NO_TIMEOUT_CTRL,
>>  + ASPEED_I2C_AC_TIMING_REG2);
>>  + }
>>  +
>>  + return 0;
>>  +}
>>  +
>>  +static void noop(struct irq_data *data) { }
>>  +
>>  +static struct irq_chip aspeed_i2c_irqchip = {
>>  + .name = "ast-i2c",
>>  + .irq_unmask = noop,
>>  + .irq_mask = noop,
>>  +};
>>  +
>>  +static int aspeed_i2c_probe_bus(struct platform_device *pdev)
>>  +{
>>  + struct aspeed_i2c_bus *bus;
>>  + struct aspeed_i2c_controller *controller =
>>  + dev_get_drvdata(pdev->dev.parent);
>>  + struct resource *res;
>>  + int ret, irq;
>>  + u32 hwirq;
>>  +
>>  + 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);
>>  + if (IS_ERR(bus->base))
>>  + return PTR_ERR(bus->base);
>>  +
>>  + bus->irq = platform_get_irq(pdev, 0);
>>  + if (bus->irq < 0)
>>  + return -ENXIO;
>>  + ret = of_property_read_u32(pdev->dev.of_node, "interrupts", &hwirq);
>>  + if (ret < 0) {
>>  + dev_err(&pdev->dev, "no I2C 'interrupts' property\n");
>>  + return -ENXIO;
>>  + }
>>  + irq = irq_create_mapping(controller->irq_domain, hwirq);
>>  + irq_set_chip_data(irq, controller);
>>  + irq_set_chip_and_handler(irq, &aspeed_i2c_irqchip, handle_simple_irq);
>>  + ret = devm_request_irq(&pdev->dev, bus->irq, aspeed_i2c_bus_irq,
>>  + 0, dev_name(&pdev->dev), bus);
>>  + if (ret) {
>>  + dev_err(&pdev->dev, "failed to request interrupt\n");
>>  + return -ENXIO;
>>  + }
>>  +
>>  + /* Initialize the I2C adapter */
>>  + spin_lock_init(&bus->lock);
>>  + init_completion(&bus->cmd_complete);
>>  + bus->adap.owner = THIS_MODULE;
>>  + bus->adap.retries = 0;
>>  + bus->adap.timeout = 5;
>>  + bus->adap.algo = &aspeed_i2c_algo;
>>  + bus->adap.algo_data = bus;
>>  + bus->adap.dev.parent = &pdev->dev;
>>  + bus->adap.dev.of_node = pdev->dev.of_node;
>>  + snprintf(bus->adap.name, sizeof(bus->adap.name), "Aspeed i2c");
>>  +
>>  + bus->dev = &pdev->dev;
>>  +
>>  + /* reset device: disable master & slave functions */
>>  + aspeed_i2c_write(bus, 0, ASPEED_I2C_FUN_CTRL_REG);
>>  +
>>  + ret = aspeed_i2c_init_clk(bus, pdev);
>>  + if (ret < 0)
>>  + return ret;
>>  +
>>  + /* Enable Master Mode */
>>  + aspeed_i2c_write(bus, aspeed_i2c_read(bus, ASPEED_I2C_FUN_CTRL_REG) |
>>  + ASPEED_I2CD_MASTER_EN |
>>  + ASPEED_I2CD_MULTI_MASTER_DIS, ASPEED_I2C_FUN_CTRL_REG);
>>  +
>>  + /* Set interrupt generation of I2C controller */
>>  + aspeed_i2c_write(bus, ASPEED_I2CD_INTR_SDA_DL_TIMEOUT |
>>  + ASPEED_I2CD_INTR_BUS_RECOVER_DONE |
>>  + ASPEED_I2CD_INTR_SCL_TIMEOUT |
>>  + ASPEED_I2CD_INTR_ABNORMAL |
>>  + ASPEED_I2CD_INTR_NORMAL_STOP |
>>  + ASPEED_I2CD_INTR_ARBIT_LOSS |
>>  + ASPEED_I2CD_INTR_RX_DONE |
>>  + ASPEED_I2CD_INTR_TX_NAK |
>>  + ASPEED_I2CD_INTR_TX_ACK,
>>  + ASPEED_I2C_INTR_CTRL_REG);
>>  +
>>  + ret = i2c_add_adapter(&bus->adap);
>>  + if (ret < 0)
>>  + return -ENXIO;
>>  +
>>  + platform_set_drvdata(pdev, bus);
>>  +
>>  + dev_info(bus->dev, "i2c bus %d registered, irq %d\n",
>>  + bus->adap.nr, bus->irq);
>>  +
>>  + return 0;
>>  +}
>>  +
>>  +static int aspeed_i2c_remove_bus(struct platform_device *pdev)
>>  +{
>>  + struct aspeed_i2c_bus *bus = platform_get_drvdata(pdev);
>>  +
>>  + i2c_del_adapter(&bus->adap);
>>  + return 0;
>>  +}
>>  +
>>  +static const struct of_device_id aspeed_i2c_bus_of_table[] = {
>>  + { .compatible = "aspeed,ast2400-i2c-bus", },
>>  + { .compatible = "aspeed,ast2500-i2c-bus", },
>>  + { },
>>  +};
>>  +MODULE_DEVICE_TABLE(of, aspeed_i2c_bus_of_table);
>>  +
>>  +static struct platform_driver aspeed_i2c_bus_driver = {
>>  + .probe = aspeed_i2c_probe_bus,
>>  + .remove = aspeed_i2c_remove_bus,
>>  + .driver = {
>>  + .name = "ast-i2c-bus",
>>  + .of_match_table = aspeed_i2c_bus_of_table,
>>  + },
>>  +};
>>  +
>>  +static void aspeed_i2c_controller_irq(struct irq_desc *desc)
>>  +{
>>  + struct aspeed_i2c_controller *c = irq_desc_get_handler_data(desc);
>>  + unsigned long p, status;
>>  + unsigned int bus_irq;
>>  +
>>  + status = readl(c->base);
>>  + for_each_set_bit(p, &status, ASPEED_I2C_NUM_BUS) {
>>  + bus_irq = irq_find_mapping(c->irq_domain, p);
>>  + generic_handle_irq(bus_irq);
>>  + }
>>  +}
>>  +
>>  +static int aspeed_i2c_probe_controller(struct platform_device *pdev)
>>  +{
>>  + struct aspeed_i2c_controller *controller;
>>  + struct device_node *np;
>>  + struct resource *res;
>>  +
>>  + controller = kzalloc(sizeof(*controller), GFP_KERNEL);
>
> use devm_kzalloc() may be ?
>
> C.
>
>>  + if (!controller)
>>  + return -ENOMEM;
>>  +
>>  + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>  + controller->base = devm_ioremap_resource(&pdev->dev, res);
>>  + if (IS_ERR(controller->base))
>>  + return PTR_ERR(controller->base);
>>  +
>>  + controller->irq = platform_get_irq(pdev, 0);
>>  + if (controller->irq < 0)
>>  + return -ENXIO;
>>  +
>>  + controller->irq_domain = irq_domain_add_linear(pdev->dev.of_node,
>>  + ASPEED_I2C_NUM_BUS, &irq_domain_simple_ops, NULL);
>>  + if (!controller->irq_domain)
>>  + return -ENXIO;
>>  + controller->irq_domain->name = "ast-i2c-domain";
>>  +
>>  + irq_set_chained_handler_and_data(controller->irq,
>>  + aspeed_i2c_controller_irq, controller);
>>  +
>>  + controller->dev = &pdev->dev;
>>  +
>>  + platform_set_drvdata(pdev, controller);
>>  +
>>  + dev_info(controller->dev, "i2c controller registered, irq %d\n",
>>  + controller->irq);
>>  +
>>  + for_each_child_of_node(pdev->dev.of_node, np) {
>>  + of_platform_device_create(np, NULL, &pdev->dev);
>>  + of_node_put(np);
>>  + }
>>  +
>>  + return 0;
>>  +}
>>  +
>>  +static int aspeed_i2c_remove_controller(struct platform_device *pdev)
>>  +{
>>  + struct aspeed_i2c_controller *controller = platform_get_drvdata(pdev);
>>  +
>>  + irq_domain_remove(controller->irq_domain);
>>  + return 0;
>>  +}
>>  +
>>  +static const struct of_device_id aspeed_i2c_controller_of_table[] = {
>>  + { .compatible = "aspeed,ast2400-i2c-controller", },
>>  + { .compatible = "aspeed,ast2500-i2c-controller", },
>>  + { },
>>  +};
>>  +MODULE_DEVICE_TABLE(of, aspeed_i2c_controller_of_table);
>>  +
>>  +static struct platform_driver aspeed_i2c_controller_driver = {
>>  + .probe = aspeed_i2c_probe_controller,
>>  + .remove = aspeed_i2c_remove_controller,
>>  + .driver = {
>>  + .name = "ast-i2c-controller",
>>  + .of_match_table = aspeed_i2c_controller_of_table,
>>  + },
>>  +};
>>  +
>>  +static int __init aspeed_i2c_driver_init(void)
>>  +{
>>  + int ret;
>>  +
>>  + ret = platform_driver_register(&aspeed_i2c_controller_driver);
>>  + if (ret < 0)
>>  + return ret;
>>  + return platform_driver_register(&aspeed_i2c_bus_driver);
>>  +}
>>  +module_init(aspeed_i2c_driver_init);
>>  +
>>  +static void __exit aspeed_i2c_driver_exit(void)
>>  +{
>>  + platform_driver_unregister(&aspeed_i2c_bus_driver);
>>  + platform_driver_unregister(&aspeed_i2c_controller_driver);
>>  +}
>>  +module_exit(aspeed_i2c_driver_exit);
>>  +
>>  +MODULE_AUTHOR("Brendan Higgins <brendanhiggins-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>");
>>  +MODULE_DESCRIPTION("Aspeed I2C Bus Driver");
>>  +MODULE_LICENSE("GPL");
>
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