On Wed, May 06, 2009 at 03:18:07PM +0200, Linus Walleij wrote:
> This adds support for the ST Microelectronics DDC I2C bus
> driver. This bus is used in the U300 architecture recently
> added to RMK:s ARM tree.
>
> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxxxxxx>
> Reviewed-by: Ben Dooks <ben-linux@xxxxxxxxx>
> Reviewed-by: Jean Delvare <khali@xxxxxxxxxxxx>
> ---
> drivers/i2c/busses/Kconfig | 12 +
> drivers/i2c/busses/Makefile | 1 +
> drivers/i2c/busses/i2c-stu300.c | 1022 +++++++++++++++++++++++++++++++++++++++
> 3 files changed, 1035 insertions(+), 0 deletions(-)
> create mode 100644 drivers/i2c/busses/i2c-stu300.c
>
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index a48c8ae..8c5d568 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -513,6 +513,18 @@ config I2C_SIMTEC
> This driver can also be built as a module. If so, the module
> will be called i2c-simtec.
>
> +config I2C_STU300
> + tristate "ST Microelectronics DDC I2C interface"
> + default y if MACH_U300
> + help
> + If you say yes to this option, support will be included for the
> + I2C interface from ST Microelectronics simply called "DDC I2C"
> + supporting both I2C and DDC, used in e.g. the U300 series
> + mobile platforms.
> +
> + This driver can also be built as a module. If so, the module
> + will be called i2c-stu300.
> +
> config I2C_VERSATILE
> tristate "ARM Versatile/Realview I2C bus support"
> depends on ARCH_VERSATILE || ARCH_REALVIEW
> diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
> index 776acb6..edeabf0 100644
> --- a/drivers/i2c/busses/Makefile
> +++ b/drivers/i2c/busses/Makefile
> @@ -48,6 +48,7 @@ obj-$(CONFIG_I2C_S6000) += i2c-s6000.o
> obj-$(CONFIG_I2C_SH7760) += i2c-sh7760.o
> obj-$(CONFIG_I2C_SH_MOBILE) += i2c-sh_mobile.o
> obj-$(CONFIG_I2C_SIMTEC) += i2c-simtec.o
> +obj-$(CONFIG_I2C_STU300) += i2c-stu300.o
> obj-$(CONFIG_I2C_VERSATILE) += i2c-versatile.o
>
> # External I2C/SMBus adapter drivers
> diff --git a/drivers/i2c/busses/i2c-stu300.c b/drivers/i2c/busses/i2c-stu300.c
> new file mode 100644
> index 0000000..2a2e569
> --- /dev/null
> +++ b/drivers/i2c/busses/i2c-stu300.c
> @@ -0,0 +1,1022 @@
> +/*
> + * Copyright (C) 2007-2009 ST-Ericsson AB
> + * License terms: GNU General Public License (GPL) version 2
> + * ST DDC I2C master mode driver, used in e.g. U300 series platforms.
> + * Author: Linus Walleij <linus.walleij@xxxxxxxxxxxxxx>
> + * Author: Jonas Aaberg <jonas.aberg@xxxxxxxxxxxxxx>
> + */
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/delay.h>
> +#include <linux/i2c.h>
> +#include <linux/spinlock.h>
> +#include <linux/completion.h>
> +#include <linux/err.h>
> +#include <linux/interrupt.h>
> +#include <linux/clk.h>
> +#include <linux/io.h>
> +
> +/* the name of this kernel module */
> +#define NAME "stu300"
> +
> +/* CR (Control Register) 8bit (R/W) */
> +#define I2C_CR (0x00000000)
> +#define I2C_CR_RESET_VALUE (0x00)
> +#define I2C_CR_RESET_UMASK (0x00)
> +#define I2C_CR_DDC1_ENABLE (0x80)
> +#define I2C_CR_TRANS_ENABLE (0x40)
> +#define I2C_CR_PERIPHERAL_ENABLE (0x20)
> +#define I2C_CR_DDC2B_ENABLE (0x10)
> +#define I2C_CR_START_ENABLE (0x08)
> +#define I2C_CR_ACK_ENABLE (0x04)
> +#define I2C_CR_STOP_ENABLE (0x02)
> +#define I2C_CR_INTERRUPT_ENABLE (0x01)
> +/* SR1 (Status Register 1) 8bit (R/-) */
> +#define I2C_SR1 (0x00000004)
> +#define I2C_SR1_RESET_VALUE (0x00)
> +#define I2C_SR1_RESET_UMASK (0x00)
> +#define I2C_SR1_EVF_IND (0x80)
> +#define I2C_SR1_ADD10_IND (0x40)
> +#define I2C_SR1_TRA_IND (0x20)
> +#define I2C_SR1_BUSY_IND (0x10)
> +#define I2C_SR1_BTF_IND (0x08)
> +#define I2C_SR1_ADSL_IND (0x04)
> +#define I2C_SR1_MSL_IND (0x02)
> +#define I2C_SR1_SB_IND (0x01)
> +/* SR2 (Status Register 2) 8bit (R/-) */
> +#define I2C_SR2 (0x00000008)
> +#define I2C_SR2_RESET_VALUE (0x00)
> +#define I2C_SR2_RESET_UMASK (0x40)
> +#define I2C_SR2_MASK (0xBF)
> +#define I2C_SR2_SCLFAL_IND (0x80)
> +#define I2C_SR2_ENDAD_IND (0x20)
> +#define I2C_SR2_AF_IND (0x10)
> +#define I2C_SR2_STOPF_IND (0x08)
> +#define I2C_SR2_ARLO_IND (0x04)
> +#define I2C_SR2_BERR_IND (0x02)
> +#define I2C_SR2_DDC2BF_IND (0x01)
> +/* CCR (Clock Control Register) 8bit (R/W) */
> +#define I2C_CCR (0x0000000C)
> +#define I2C_CCR_RESET_VALUE (0x00)
> +#define I2C_CCR_RESET_UMASK (0x00)
> +#define I2C_CCR_MASK (0xFF)
> +#define I2C_CCR_FMSM (0x80)
> +#define I2C_CCR_CC_MASK (0x7F)
> +/* OAR1 (Own Address Register 1) 8bit (R/W) */
> +#define I2C_OAR1 (0x00000010)
> +#define I2C_OAR1_RESET_VALUE (0x00)
> +#define I2C_OAR1_RESET_UMASK (0x00)
> +#define I2C_OAR1_ADD_MASK (0xFF)
> +/* OAR2 (Own Address Register 2) 8bit (R/W) */
> +#define I2C_OAR2 (0x00000014)
> +#define I2C_OAR2_RESET_VALUE (0x40)
> +#define I2C_OAR2_RESET_UMASK (0x19)
> +#define I2C_OAR2_MASK (0xE6)
> +#define I2C_OAR2_FR_25_10MHZ (0x00)
> +#define I2C_OAR2_FR_10_1667MHZ (0x20)
> +#define I2C_OAR2_FR_1667_2667MHZ (0x40)
> +#define I2C_OAR2_FR_2667_40MHZ (0x60)
> +#define I2C_OAR2_FR_40_5333MHZ (0x80)
> +#define I2C_OAR2_FR_5333_66MHZ (0xA0)
> +#define I2C_OAR2_FR_66_80MHZ (0xC0)
> +#define I2C_OAR2_FR_80_100MHZ (0xE0)
> +#define I2C_OAR2_FR_MASK (0xE0)
> +#define I2C_OAR2_ADD_MASK (0x06)
> +/* DR (Data Register) 8bit (R/W) */
> +#define I2C_DR (0x00000018)
> +#define I2C_DR_RESET_VALUE (0x00)
> +#define I2C_DR_RESET_UMASK (0xFF)
> +#define I2C_DR_D_MASK (0xFF)
> +/* ECCR (Extended Clock Control Register) 8bit (R/W) */
> +#define I2C_ECCR (0x0000001C)
> +#define I2C_ECCR_RESET_VALUE (0x00)
> +#define I2C_ECCR_RESET_UMASK (0xE0)
> +#define I2C_ECCR_MASK (0x1F)
> +#define I2C_ECCR_CC_MASK (0x1F)
> +
> +/*
> + * These events are more or less responses to commands
> + * sent into the hardware, presumably reflecting the state
> + * of an internal state machine.
> + */
> +enum stu300_event {
> + STU300_EVENT_NONE = 0,
> + STU300_EVENT_1,
> + STU300_EVENT_2,
> + STU300_EVENT_3,
> + STU300_EVENT_4,
> + STU300_EVENT_5,
> + STU300_EVENT_6,
> + STU300_EVENT_7,
> + STU300_EVENT_8,
> + STU300_EVENT_9
> +};
> +
> +enum stu300_error {
> + STU300_ERROR_NONE = 0,
> + STU300_ERROR_ACKNOWLEDGE_FAILURE,
> + STU300_ERROR_BUS_ERROR,
> + STU300_ERROR_ARBITRATION_LOST
> +};
> +
> +/* timeout waiting for the controller to respond */
> +#define STU300_TIMEOUT (msecs_to_jiffies(1000))
> +
> +/*
> + * The number of address send athemps tried before giving up.
> + * If the first one failes it seems like 5 to 8 attempts are required.
> + */
> +#define NUM_ADDR_RESEND_ATTEMPTS 10
> +
> +/* I2C clock speed, in Hz 0-400kHz*/
> +static unsigned int scl_frequency = 100000;
> +module_param(scl_frequency, uint, 0644);
> +
> +struct stu300_dev {
> + /* Parent platform device */
> + struct platform_device *pdev;
> + /* Corresponding I2C adapter */
> + struct i2c_adapter adapter;
> + /* Location of I/O area in memory, and size */
> + u32 phybase;
> + u32 physize;
if you're using resource_size, then I belive this should
really be a resource_size_t otherwise you'll be casting
down from u64 if you've got 64bit resources enabled.
> + void __iomem *virtbase;
> + /* Hardware block clock */
> + struct clk *clk;
> + /* Assigned interrupt line */
> + int irq;
> + /* This locks the following cmd_ variables */
> + spinlock_t cmd_issue_lock;
> + /* Acknowledge completion for I2C command */
> + struct completion cmd_complete;
> + /* Event coming in as a response to a command */
> + enum stu300_event cmd_event;
> + /* Error code as response to a command */
> + enum stu300_error cmd_err;
> + /* Current bus speed, in Hz */
> + unsigned int speed;
> + /* Index and length of current message */
> + int msg_index;
> + int msg_len;
> +};
kerneldoc please.
> +
> +/* Local forward function declarations */
> +static int stu300_init_hw(struct stu300_dev *dev);
> +
> +/*
> + * The block needs writes in both MSW and LSW in order
> + * for all data lines to reach their destination.
> + */
> +static inline void stu300_wr8(u32 value, void __iomem *address)
> +{
> + writel((value << 16) | value, address);
> +}
> +
> +/*
> + * This merely masks off the duplicates which appear
> + * in bytes 1-3.
> + */
> +static inline u32 stu300_r8(void __iomem *address)
> +{
> + return readl(address) & 0x000000FFU;
> +}
did readb not work for you? if so, please comment in here
otherwise other people might make the same mistake.
> +/*
> + * Tells whether a certain event or events occurred in
> + * response to a command. The events represent states in
> + * the internal state machine of the hardware. The events
> + * are not very well described in the hardware
> + * documentation and can only be treated as abstract state
> + * machine states.
> + *
> + * @ret 0 = event has not occurred, any other value means
> + * the event occurred.
> + */
> +static int stu300_event_occurred(struct stu300_dev *dev,
> + enum stu300_event mr_event) {
> + u32 status1;
> + u32 status2;
> +
> + /* What event happened? */
> + status1 = stu300_r8(dev->virtbase + I2C_SR1);
> + if (!(status1 & I2C_SR1_EVF_IND))
> + /* No event at all */
> + return 0;
> + status2 = stu300_r8(dev->virtbase + I2C_SR2);
> +
> + switch (mr_event) {
> + case STU300_EVENT_1:
> + if (status1 & I2C_SR1_ADSL_IND)
> + return 1;
> + break;
> + case STU300_EVENT_2:
> + case STU300_EVENT_3:
> + case STU300_EVENT_7:
> + case STU300_EVENT_8:
> + if (status1 & I2C_SR1_BTF_IND) {
> + if (status2 & I2C_SR2_AF_IND)
> + dev->cmd_err = STU300_ERROR_ACKNOWLEDGE_FAILURE;
> + else if (status2 & I2C_SR2_BERR_IND)
> + dev->cmd_err = STU300_ERROR_BUS_ERROR;
> + return 1;
> + }
> + break;
> + case STU300_EVENT_4:
> + if (status2 & I2C_SR2_STOPF_IND)
> + return 1;
> + break;
> + case STU300_EVENT_5:
> + if (status1 & I2C_SR1_SB_IND)
> + /* Clear start bit */
> + return 1;
> + break;
> + case STU300_EVENT_6:
> + if (status2 & I2C_SR2_ENDAD_IND) {
> + /* First check for any errors */
> + if (status2 & I2C_SR2_AF_IND)
> + dev->cmd_err = STU300_ERROR_ACKNOWLEDGE_FAILURE;
> + return 1;
> + }
> + break;
> + case STU300_EVENT_9:
> + if (status1 & I2C_SR1_ADD10_IND)
> + return 1;
> + break;
> + default:
> + break;
> + }
> + if (status2 & I2C_SR2_ARLO_IND)
> + dev->cmd_err = STU300_ERROR_ARBITRATION_LOST;
> + return 0;
> +}
> +
> +static irqreturn_t stu300_irh(int irq, void *data)
> +{
> + struct stu300_dev *dev = data;
> + int res;
> +
> + /* See if this was what we were waiting for */
> + spin_lock(&dev->cmd_issue_lock);
> + if (dev->cmd_event != STU300_EVENT_NONE) {
> + res = stu300_event_occurred(dev, dev->cmd_event);
> + if (res || dev->cmd_err != STU300_ERROR_NONE) {
> + u32 val;
> +
> + complete(&dev->cmd_complete);
> + /* Block any multiple interrupts */
> + val = stu300_r8(dev->virtbase + I2C_CR);
> + val &= ~I2C_CR_INTERRUPT_ENABLE;
> + stu300_wr8(val, dev->virtbase + I2C_CR);
> + }
> + }
> + spin_unlock(&dev->cmd_issue_lock);
> + return IRQ_HANDLED;
> +}
> +
> +/*
> + * Sends a command and then waits for the bits masked by *flagmask*
> + * to go high or low by IRQ awaiting.
> + */
> +static int stu300_start_and_await_event(struct stu300_dev *dev,
> + u8 cr_value,
> + enum stu300_event mr_event)
> +{
> + int ret;
> +
> + if (unlikely(irqs_disabled())) {
> + /* TODO: implement polling for this case if need be. */
> + dev_err(&dev->pdev->dev, "irqs are disabled on this "
> + "system!\n");
> + return -EIO;
> + }
how about saying "irqs disabled, cannot poll for event", makes a bit
more sense... do you want to add a WARN_ON(1) to give the user a
backtrace (or WARN_ON_ONCE(1)) ?
> + /* Lock command issue, fill in an event we wait for */
> + spin_lock_irq(&dev->cmd_issue_lock);
> + init_completion(&dev->cmd_complete);
> + dev->cmd_err = STU300_ERROR_NONE;
> + dev->cmd_event = mr_event;
> + spin_unlock_irq(&dev->cmd_issue_lock);
> +
> + /* Turn on interrupt, send command and wait. */
> + cr_value |= I2C_CR_INTERRUPT_ENABLE;
> + stu300_wr8(cr_value, dev->virtbase + I2C_CR);
> + ret = wait_for_completion_interruptible_timeout(&dev->cmd_complete,
> + STU300_TIMEOUT);
> +
> + if (ret < 0) {
> + dev_err(&dev->pdev->dev,
> + "wait_for_completion_interruptible_timeout() "
> + "returned %d waiting for event %04x\n", ret, mr_event);
> + return ret;
> + }
> +
> + if (ret == 0) {
> + dev_err(&dev->pdev->dev, "controller timed out "
> + "waiting for event %d, reinit hardware\n", mr_event);
> + (void) stu300_init_hw(dev);
> + return -ETIMEDOUT;
> + }
> +
> + if (dev->cmd_err != STU300_ERROR_NONE) {
> + dev_err(&dev->pdev->dev, "controller (start) "
> + "error %d waiting for event %d, reinit hardware\n",
> + dev->cmd_err, mr_event);
> + (void) stu300_init_hw(dev);
> + return -EIO;
> + }
> +
> + return 0;
> +}
> +
> +/*
> + * This waits for a flag to be set, if it is not set on entry, an interrupt is
> + * configured to wait for the flag using a completion.
> + */
> +static int stu300_await_event(struct stu300_dev *dev,
> + enum stu300_event mr_event)
> +{
> + int ret;
> + u32 val;
> +
> + if (unlikely(irqs_disabled())) {
> + /* TODO: implement polling for this case if need be. */
> + dev_err(&dev->pdev->dev, "irqs are disabled on this "
> + "system!\n");
> + return -EIO;
> + }
> +
> + /* Is it already here? */
> + spin_lock_irq(&dev->cmd_issue_lock);
> + dev->cmd_err = STU300_ERROR_NONE;
> + if (stu300_event_occurred(dev, mr_event)) {
> + spin_unlock_irq(&dev->cmd_issue_lock);
> + goto exit_await_check_err;
> + }
> + init_completion(&dev->cmd_complete);
> + dev->cmd_err = STU300_ERROR_NONE;
> + dev->cmd_event = mr_event;
> +
> + /* Turn on the I2C interrupt for current operation */
> + val = stu300_r8(dev->virtbase + I2C_CR);
> + val |= I2C_CR_INTERRUPT_ENABLE;
> + stu300_wr8(val, dev->virtbase + I2C_CR);
> +
> + /* Twice paranoia (possible HW glitch) */
> + stu300_wr8(val, dev->virtbase + I2C_CR);
> +
> + /* Check again: is it already here? */
> + if (unlikely(stu300_event_occurred(dev, mr_event))) {
> + /* Disable IRQ again. */
> + val &= ~I2C_CR_INTERRUPT_ENABLE;
> + stu300_wr8(val, dev->virtbase + I2C_CR);
> + spin_unlock_irq(&dev->cmd_issue_lock);
> + goto exit_await_check_err;
> + }
> +
> + /* Unlock the command block and wait for the event to occur */
> + spin_unlock_irq(&dev->cmd_issue_lock);
> + ret = wait_for_completion_interruptible_timeout(&dev->cmd_complete,
> + STU300_TIMEOUT);
> +
> + if (ret < 0) {
> + dev_err(&dev->pdev->dev,
> + "wait_for_completion_interruptible_timeout()"
> + "returned %d waiting for event %04x\n", ret, mr_event);
> + return ret;
> + }
> +
> + if (ret == 0) {
> + if (mr_event != STU300_EVENT_6) {
> + dev_err(&dev->pdev->dev, "controller "
> + "timed out waiting for event %d, reinit "
> + "hardware\n", mr_event);
> + (void) stu300_init_hw(dev);
> + }
> + return -ETIMEDOUT;
> + }
> +
> + exit_await_check_err:
> + if (dev->cmd_err != STU300_ERROR_NONE) {
> + if (mr_event != STU300_EVENT_6) {
> + dev_err(&dev->pdev->dev, "controller "
> + "error (await_event) %d waiting for event %d, "
> + "reinit hardware\n", dev->cmd_err, mr_event);
> + (void) stu300_init_hw(dev);
> + }
> + return -EIO;
> + }
> +
> + return 0;
> +}
> +
> +/*
> + * Waits for the busy bit to go low by repeated polling.
> + */
> +#define BUSY_RELEASE_ATTEMPTS 10
> +static int stu300_wait_while_busy(struct stu300_dev *dev)
> +{
> + unsigned long timeout;
> + int i;
> +
> + for (i = 0; i < BUSY_RELEASE_ATTEMPTS; i++) {
> + timeout = jiffies + STU300_TIMEOUT;
> +
> + while (!time_after(jiffies, timeout)) {
> + /* Is not busy? */
> + if ((stu300_r8(dev->virtbase + I2C_SR1) &
> + I2C_SR1_BUSY_IND) == 0)
> + return 0;
> + msleep(1);
> + }
> +
> + dev_err(&dev->pdev->dev, "transaction timed out "
> + "waiting for device to be free (not busy). "
> + "Attempt: %d\n", i+1);
> +
> + dev_err(&dev->pdev->dev, "base address = "
> + "0x%08x, reinit hardware\n", (u32) dev->virtbase);
> +
> + (void) stu300_init_hw(dev);
> + }
> +
> + dev_err(&dev->pdev->dev, "giving up after %d attempts "
> + "to reset the bus.\n", BUSY_RELEASE_ATTEMPTS);
> +
> + return -ETIMEDOUT;
> +}
> +
> +struct stu300_clkset {
> + unsigned long rate;
> + u32 setting;
> +};
> +
> +static const struct stu300_clkset stu300_clktable[] = {
> + { 0, 0xFFU },
> + { 2500000, I2C_OAR2_FR_25_10MHZ },
> + { 10000000, I2C_OAR2_FR_10_1667MHZ },
> + { 16670000, I2C_OAR2_FR_1667_2667MHZ },
> + { 26670000, I2C_OAR2_FR_2667_40MHZ },
> + { 40000000, I2C_OAR2_FR_40_5333MHZ },
> + { 53330000, I2C_OAR2_FR_5333_66MHZ },
> + { 66000000, I2C_OAR2_FR_66_80MHZ },
> + { 80000000, I2C_OAR2_FR_80_100MHZ },
> + { 100000000, 0xFFU },
> +};
> +
> +static int stu300_set_clk(struct stu300_dev *dev, unsigned long clkrate)
> +{
> +
> + u32 val;
> + int i = 0;
> +
> + /* Locate the apropriate clock setting */
> + while (i < ARRAY_SIZE(stu300_clktable) &&
> + stu300_clktable[i].rate < clkrate)
> + i++;
> +
> + if (stu300_clktable[i].setting == 0xFFU) {
> + dev_err(&dev->pdev->dev, "too %s clock rate requested "
> + "(%lu Hz).\n", i ? "high" : "low", clkrate);
> + return -EINVAL;
> + }
> +
> + stu300_wr8(stu300_clktable[i].setting,
> + dev->virtbase + I2C_OAR2);
> +
> + dev_dbg(&dev->pdev->dev, "Clock rate %lu Hz, I2C bus speed %d Hz "
> + "virtbase %p\n", clkrate, dev->speed, dev->virtbase);
> +
> + if (dev->speed > 100000)
> + /* Fast Mode I2C */
> + val = ((clkrate/dev->speed)-9)/3;
> + else
> + /* Standard Mode I2C */
> + val = ((clkrate/dev->speed)-7)/2;
> +
> + /* According to spec the divider must be > 2 */
> + if (val < 0x002) {
> + dev_err(&dev->pdev->dev, "too low clock rate (%lu Hz).\n",
> + clkrate);
> + return -EINVAL;
> + }
> +
> + /* We have 12 bits clock divider only! */
> + if (val & 0xFFFFF000U) {
> + dev_err(&dev->pdev->dev, "too high clock rate (%lu Hz).\n",
> + clkrate);
> + return -EINVAL;
> + }
> +
> + if (dev->speed > 100000) {
> + /* CC6..CC0 */
> + stu300_wr8((val & I2C_CCR_CC_MASK) | I2C_CCR_FMSM,
> + dev->virtbase + I2C_CCR);
>
alignmnt of second arg?
+ dev_dbg(&dev->pdev->dev, "set clock divider to 0x%08x, "
> + "Fast Mode I2C\n", val);
> + } else {
> + /* CC6..CC0 */
> + stu300_wr8((val & I2C_CCR_CC_MASK),
> + dev->virtbase + I2C_CCR);
> + dev_dbg(&dev->pdev->dev, "set clock divider to "
> + "0x%08x, Standard Mode I2C\n", val);
> + }
> +
> + /* CC11..CC7 */
> + stu300_wr8(((val >> 7) & 0x1F),
> + dev->virtbase + I2C_ECCR);
> +
> + return 0;
> +}
> +
> +
> +static int stu300_init_hw(struct stu300_dev *dev)
> +{
> + u32 dummy;
> + unsigned long clkrate;
> + int ret;
> +
> + /* Disable controller */
> + stu300_wr8(0x00, dev->virtbase + I2C_CR);
> + /*
> + * Set own address to some default value (0x00).
> + * We do not support slave mode anyway.
> + */
> + stu300_wr8(0x00, dev->virtbase + I2C_OAR1);
> + /*
> + * The I2C controller only operates properly in 26 MHz but we
> + * program this driver as if we didn't know. This will also set the two
> + * high bits of the own address to zero as well.
> + * There is no known hardware issue with running in 13 MHz
> + * However, speeds over 200 kHz are not used.
> + */
> + clkrate = clk_get_rate(dev->clk);
> + ret = stu300_set_clk(dev, clkrate);
> + if (ret)
> + return ret;
> + /*
> + * Enable block, do it TWICE (hardware glitch)
> + * Setting bit 7 can enable DDC mode. (Not used currently.)
> + */
> + stu300_wr8(I2C_CR_PERIPHERAL_ENABLE,
> + dev->virtbase + I2C_CR);
> + stu300_wr8(I2C_CR_PERIPHERAL_ENABLE,
> + dev->virtbase + I2C_CR);
> + /* Make a dummy read of the status register SR1 & SR2 */
> + dummy = stu300_r8(dev->virtbase + I2C_SR2);
> + dummy = stu300_r8(dev->virtbase + I2C_SR1);
> +
> + return 0;
> +}
> +
> +
> +
> +/* Send slave address. */
> +static int stu300_send_address(struct stu300_dev *dev,
> + struct i2c_msg *msg, int resend)
> +{
> + u32 val;
> + int ret;
> +
> + if (msg->flags & I2C_M_TEN)
> + /* This is probably how 10 bit addresses look */
> + val = (0xf0 | (((u32) msg->addr & 0x300) >> 7)) &
> + I2C_DR_D_MASK;
> + else
> + val = ((msg->addr << 1) & I2C_DR_D_MASK);
> +
> + if (msg->flags & I2C_M_RD) {
> + /* This is the direction bit */
> + val |= 0x01;
> + if (resend)
> + dev_dbg(&dev->pdev->dev, "read resend\n");
> + } else if (resend)
> + dev_dbg(&dev->pdev->dev, "write resend\n");
> + stu300_wr8(val, dev->virtbase + I2C_DR);
> +
> + /* For 10bit addressing, await 10bit request (EVENT 9) */
> + if (msg->flags & I2C_M_TEN) {
> + ret = stu300_await_event(dev, STU300_EVENT_9);
> + /*
> + * The slave device wants a 10bit address, send the rest
> + * of the bits (the LSBits)
> + */
> + val = msg->addr & I2C_DR_D_MASK;
> + /* This clears "event 9" */
> + stu300_wr8(val, dev->virtbase + I2C_DR);
> + if (ret != 0)
> + return ret;
> + }
> + /* FIXME: Why no else here? two events for 10bit?
> + * Await event 6 (normal) or event 9 (10bit)
> + */
> +
> + if (resend)
> + dev_dbg(&dev->pdev->dev, "await event 6\n");
> + ret = stu300_await_event(dev, STU300_EVENT_6);
> +
> + /*
> + * Clear any pending EVENT 6 no matter what happend during
> + * await_event.
> + */
> + val = stu300_r8(dev->virtbase + I2C_CR);
> + val |= I2C_CR_PERIPHERAL_ENABLE;
> + stu300_wr8(val, dev->virtbase + I2C_CR);
> +
> + return ret;
> +}
> +
> +static int stu300_xfer_msg(struct i2c_adapter *adap,
> + struct i2c_msg *msg, int stop)
> +{
> + u32 cr;
> + u32 val;
> + u32 i;
> + int ret;
> + int attempts = 0;
> + struct stu300_dev *dev = i2c_get_adapdata(adap);
> +
> +
> + clk_enable(dev->clk);
> +
> + /* Remove this if (0) to trace each and every message. */
> + if (0) {
> + dev_dbg(&dev->pdev->dev, "I2C message to: 0x%04x, len: %d, "
> + "flags: 0x%04x, stop: %d\n",
> + msg->addr, msg->len, msg->flags, stop);
> + }
> +
> + /* Zero-length messages are not supported by this hardware */
> + if (msg->len == 0) {
> + ret = -EINVAL;
> + goto exit_disable;
> + }
> +
> + /*
> + * For some reason, sending the address sometimes fails when running
> + * on the 13 MHz clock. No interrupt arrives. This is a work around,
> + * which tries to restart and send the address up to 10 times before
> + * really giving up. Usually 5 to 8 attempts are enough.
> + */
> + do {
> + if (attempts)
> + dev_dbg(&dev->pdev->dev, "wait while busy\n");
> + /* Check that the bus is free, or wait until some timeout */
> + ret = stu300_wait_while_busy(dev);
> + if (ret != 0)
> + goto exit_disable;
> +
> + if (attempts)
> + dev_dbg(&dev->pdev->dev, "re-int hw\n");
> + /*
> + * According to ST, there is no problem if the clock is
> + * changed between 13 and 26 MHz during a transfer.
> + */
> + ret = stu300_init_hw(dev);
> + if (ret)
> + goto exit_disable;
> +
> + /* Send a start condition */
> + cr = I2C_CR_PERIPHERAL_ENABLE;
> + /* Setting the START bit puts the block in master mode */
> + if (!(msg->flags & I2C_M_NOSTART))
> + cr |= I2C_CR_START_ENABLE;
> + if ((msg->flags & I2C_M_RD) && (msg->len > 1))
> + /* On read more than 1 byte, we need ack. */
> + cr |= I2C_CR_ACK_ENABLE;
> + /* Check that it gets through */
> + if (!(msg->flags & I2C_M_NOSTART)) {
> + if (attempts)
> + dev_dbg(&dev->pdev->dev, "send start event\n");
> + ret = stu300_start_and_await_event(dev, cr,
> + STU300_EVENT_5);
> + }
> +
> + if (attempts)
> + dev_dbg(&dev->pdev->dev, "send address\n");
> +
> + if (ret == 0)
> + /* Send address */
> + ret = stu300_send_address(dev, msg, attempts != 0);
> +
> + if (ret != 0) {
> + attempts++;
> + dev_dbg(&dev->pdev->dev, "failed sending address, "
> + "retrying. Attempt: %d msg_index: %d/%d\n",
> + attempts, dev->msg_index, dev->msg_len);
> + }
> +
> + } while (ret != 0 && attempts < NUM_ADDR_RESEND_ATTEMPTS);
> +
> + if (attempts < NUM_ADDR_RESEND_ATTEMPTS && attempts > 0) {
> + dev_dbg(&dev->pdev->dev, "managed to get address "
> + "through after %d attempts\n", attempts);
> + } else if (attempts == NUM_ADDR_RESEND_ATTEMPTS) {
> + dev_dbg(&dev->pdev->dev, "I give up, tried %d times "
> + "to resend address.\n",
> + NUM_ADDR_RESEND_ATTEMPTS);
> + goto exit_disable;
> + }
> +
> + if (msg->flags & I2C_M_RD) {
> + /* READ: we read the actual bytes one at a time */
> + for (i = 0; i < msg->len; i++) {
> + if (i == msg->len-1) {
> + /*
> + * Disable ACK and set STOP condition before
> + * reading last byte
> + */
> + val = I2C_CR_PERIPHERAL_ENABLE;
> +
> + if (stop)
> + val |= I2C_CR_STOP_ENABLE;
> +
> + stu300_wr8(val,
> + dev->virtbase + I2C_CR);
> + }
> + /* Wait for this byte... */
> + ret = stu300_await_event(dev, STU300_EVENT_7);
> + if (ret != 0)
> + goto exit_disable;
> + /* This clears event 7 */
> + msg->buf[i] = (u8) stu300_r8(dev->virtbase + I2C_DR);
> + }
> + } else {
> + /* WRITE: we send the actual bytes one at a time */
> + for (i = 0; i < msg->len; i++) {
> + /* Write the byte */
> + stu300_wr8(msg->buf[i],
> + dev->virtbase + I2C_DR);
> + /* Check status */
> + ret = stu300_await_event(dev, STU300_EVENT_8);
> + /* Next write to DR will clear event 8 */
> + if (ret != 0) {
> + dev_err(&dev->pdev->dev, "error awaiting "
> + "event 8 (%d)\n", ret);
> + goto exit_disable;
> + }
> + }
> + /* Check NAK */
> + if (!(msg->flags & I2C_M_IGNORE_NAK)) {
> + if (stu300_r8(dev->virtbase + I2C_SR2) &
> + I2C_SR2_AF_IND) {
> + dev_err(&dev->pdev->dev, "I2C payload "
> + "send returned NAK!\n");
> + ret = -EIO;
> + goto exit_disable;
> + }
> + }
> + if (stop) {
> + /* Send stop condition */
> + val = I2C_CR_PERIPHERAL_ENABLE;
> + val |= I2C_CR_STOP_ENABLE;
> + stu300_wr8(val, dev->virtbase + I2C_CR);
> + }
> + }
> +
> + /* Check that the bus is free, or wait until some timeout occurs */
> + ret = stu300_wait_while_busy(dev);
> + if (ret != 0) {
> + dev_err(&dev->pdev->dev, "timout waiting for transfer "
> + "to commence.\n");
> + goto exit_disable;
> + }
> +
> + /* Dummy read status registers */
> + val = stu300_r8(dev->virtbase + I2C_SR2);
> + val = stu300_r8(dev->virtbase + I2C_SR1);
> + ret = 0;
> +
> + exit_disable:
> + /* Disable controller */
> + stu300_wr8(0x00, dev->virtbase + I2C_CR);
> + clk_disable(dev->clk);
> + return ret;
> +}
> +
> +static int stu300_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
> + int num)
> +{
> + int ret = -1;
> + int i;
> + struct stu300_dev *dev = i2c_get_adapdata(adap);
> + dev->msg_len = num;
> + for (i = 0; i < num; i++) {
> + /*
> + * Another driver appears to send stop for each message,
> + * here we only do that for the last message. Possibly some
> + * peripherals require this behaviour, then their drivers
> + * have to send single messages in order to get "stop" for
> + * each message.
> + */
I think that is right, although i'd have to check to be sure.
> + dev->msg_index = i;
> +
> + ret = stu300_xfer_msg(adap, &msgs[i], (i == (num - 1)));
> + if (ret != 0) {
> + num = ret;
> + break;
> + }
> + }
> +
> + return num;
> +}
> +
> +static u32 stu300_func(struct i2c_adapter *adap)
> +{
> + /* This is the simplest thing you can think of... */
> + return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR;
> +}
> +
> +static const struct i2c_algorithm stu300_algo = {
> + .master_xfer = stu300_xfer,
> + .functionality = stu300_func,
> +};
> +
> +static int __init
> +stu300_probe(struct platform_device *pdev)
> +{
> + struct stu300_dev *dev;
> + struct i2c_adapter *adap;
> + struct resource *res;
> + int bus_nr;
> + int ret = 0;
> +
> + dev = kzalloc(sizeof(struct stu300_dev), GFP_KERNEL);
> + if (!dev) {
> + ret = -ENOMEM;
> + goto err_no_devmem;
> + }
no handy little error message here?
> + bus_nr = pdev->id;
> + dev->clk = clk_get(&pdev->dev, NULL);
> + if (IS_ERR(dev->clk)) {
> + ret = PTR_ERR(dev->clk);
> + dev_err(&pdev->dev, "could not retrieve i2c bus clock\n");
> + goto err_no_clk;
> + }
> +
> + dev->pdev = pdev;
> + platform_set_drvdata(pdev, dev);
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (!res) {
> + ret = -ENOENT;
> + goto err_no_resource;
> + }
> +
> + dev->phybase = res->start;
> + dev->physize = resource_size(res);
> +
> + if (request_mem_region(dev->phybase, dev->physize,
> + NAME " I/O Area") == NULL) {
> + ret = -EBUSY;
> + goto err_no_ioregion;
> + }
> +
> + dev->virtbase = ioremap(dev->phybase, dev->physize);
> + dev_dbg(&pdev->dev, "initialize bus device I2C%d on virtual "
> + "base 0x%08x\n", bus_nr, (u32) dev->virtbase);
hmm, wouldn't %p work better than cast to (u32) ?
> + if (!dev->virtbase) {
> + ret = -ENOMEM;
> + goto err_no_ioremap;
> + }
> +
> + dev->irq = platform_get_irq(pdev, 0);
> + if (request_irq(dev->irq, stu300_irh, IRQF_DISABLED,
> + NAME, dev)) {
> + ret = -EIO;
> + goto err_no_irq;
> + }
> +
> + dev->speed = scl_frequency;
> +
> + clk_enable(dev->clk);
> + ret = stu300_init_hw(dev);
> + clk_disable(dev->clk);
> +
> + if (ret != 0) {
> + dev_err(&dev->pdev->dev, "error initializing hardware.\n");
> + goto err_init_hw;
> + }
> +
> + /* IRQ event handling initialization */
> + spin_lock_init(&dev->cmd_issue_lock);
> + dev->cmd_event = STU300_EVENT_NONE;
> + dev->cmd_err = STU300_ERROR_NONE;
> +
> + adap = &dev->adapter;
> + adap->owner = THIS_MODULE;
> + /* DDC class but actually often used for more generic I2C */
> + adap->class = I2C_CLASS_DDC;
> + strncpy(adap->name, "ST Microelectronics DDC I2C adapter",
> + sizeof(adap->name));
> + adap->nr = bus_nr;
> + adap->algo = &stu300_algo;
> + adap->dev.parent = &pdev->dev;
> + i2c_set_adapdata(adap, dev);
> +
> + /* i2c device drivers may be active on return from add_adapter() */
> + ret = i2c_add_numbered_adapter(adap);
> + if (ret) {
> + dev_err(&dev->pdev->dev, "failure adding ST Micro DDC "
> + "I2C adapter\n");
> + goto err_add_adapter;
> + }
> + return 0;
> +
> + err_add_adapter:
> + err_init_hw:
> + free_irq(dev->irq, dev);
> + err_no_irq:
> + iounmap(dev->virtbase);
> + err_no_ioremap:
> + release_mem_region(dev->phybase, dev->physize);
> + err_no_ioregion:
> + platform_set_drvdata(pdev, NULL);
> + err_no_resource:
> + clk_put(dev->clk);
> + err_no_clk:
> + kfree(dev);
> + err_no_devmem:
> + dev_err(&pdev->dev, "failed to add " NAME " adapter: %d\n",
> + pdev->id);
> + return ret;
> +}
> +
> +#ifdef CONFIG_PM
> +static int stu300_suspend(struct platform_device *pdev, pm_message_t state)
> +{
> + struct stu300_dev *dev = platform_get_drvdata(pdev);
> +
> + /* Turn off everything */
> + stu300_wr8(0x00, dev->virtbase + I2C_CR);
> + return 0;
> +}
> +
> +static int stu300_resume(struct platform_device *pdev)
> +{
> + int ret = 0;
> + struct stu300_dev *dev = platform_get_drvdata(pdev);
> +
> + clk_enable(dev->clk);
> + ret = stu300_init_hw(dev);
> + clk_disable(dev->clk);
> +
> + if (ret != 0)
> + dev_err(&pdev->dev, "error re-initializing hardware.\n");
> + return ret;
> +}
> +#else
> +#define stu300_suspend NULL
> +#define stu300_resume NULL
> +#endif
> +
> +static int __exit
> +stu300_remove(struct platform_device *pdev)
> +{
> + struct stu300_dev *dev = platform_get_drvdata(pdev);
> +
> + i2c_del_adapter(&dev->adapter);
> + /* Turn off everything */
> + stu300_wr8(0x00, dev->virtbase + I2C_CR);
> + free_irq(dev->irq, dev);
> + iounmap(dev->virtbase);
> + release_mem_region(dev->phybase, dev->physize);
> + clk_put(dev->clk);
> + platform_set_drvdata(pdev, NULL);
> + kfree(dev);
> + return 0;
> +}
> +
> +static struct platform_driver stu300_i2c_driver = {
> + .driver = {
> + .name = NAME,
> + .owner = THIS_MODULE,
> + },
> + .remove = __exit_p(stu300_remove),
> + .suspend = stu300_suspend,
> + .resume = stu300_resume,
> +
> +};
> +
> +static int __init stu300_init(void)
> +{
> + return platform_driver_probe(&stu300_i2c_driver, stu300_probe);
> +}
> +
> +static void __exit stu300_exit(void)
> +{
> + platform_driver_unregister(&stu300_i2c_driver);
> +}
> +
> +/*
> + * The systems using this bus often have very basic devices such
> + * as regulators on the I2C bus, so this needs to be loaded early.
> + * Therefore it is registered in the subsys_initcall().
> + */
> +subsys_initcall(stu300_init);
> +module_exit(stu300_exit);
> +
> +MODULE_AUTHOR("Linus Walleij <linus.walleij@xxxxxxxxxxxxxx>");
> +MODULE_DESCRIPTION("ST Micro DDC I2C adapter (stu300)");
> +MODULE_LICENSE("GPL");
I think you missed the platform device MODULE_ALIAS() as well, so
no udev autoloading for you!
--
Ben (ben@xxxxxxxxx, http://www.fluff.org/)
'a smiley only costs 4 bytes'
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