Fwd: [PATCH v7] i2c: exynos5: add High Speed I2C controller driver

Naveen Krishna Ch
2013-05-01T23:19:58Z

On 16 April 2013 15:59, Wolfram Sang <wsa@the-dreams.de> wrote:
> Hi,
>
> thanks for the submission.
>
> On Thu, Apr 04, 2013 at 09:52:01PM -0700, Naveen Krishna Chatradhi wrote:
>> From: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
>>
>> Adds support for High Speed I2C driver found in Exynos5 and
>> later SoCs from Samsung.
>> This driver currently supports Auto mode.
>
> Either explain the limitation of this mode or just leave this sentence.
Sure will add bit more explanation
>
>> Driver only supports Device Tree method.
>> Note: Added debugfs support for registers view, not tested.
>
> Then leave it out, please.
I prefer leave it out for now.
>
>>
>> Signed-off-by: Taekgyun Ko <taeggyun.ko@samsung.com>
>> Signed-off-by: Naveen Krishna Chatradhi <ch.naveen@samsung.com>
>> Reviewed-by: Simon Glass <sjg@google.com>
>> Tested-by: Andrew Bresticker <abrestic@google.com>
>> ---
>> change since v6:
>> 1. clock divisor function hs split to handle the error cases
>> 2. Other irq types are handled
>> 3. FIFO are handled more efficiently in TX and RX
>> 4. More function description added
>> 5. handled the return cases in xfer_msg function
>>
>> .../devicetree/bindings/i2c/i2c-exynos5.txt | 50 ++
>> drivers/i2c/busses/Kconfig | 7 +
>> drivers/i2c/busses/Makefile | 1 +
>> drivers/i2c/busses/i2c-exynos5.c | 934 ++++++++++++++++++++
>> 4 files changed, 992 insertions(+)
>> create mode 100644 Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
>> create mode 100644 drivers/i2c/busses/i2c-exynos5.c
>>
>> diff --git a/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt b/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
>> new file mode 100644
>> index 0000000..0bc9347
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/i2c/i2c-exynos5.txt
>> @@ -0,0 +1,50 @@
>> +* Samsung's High Speed I2C controller
>> +
>> +The Samsung's High Speed I2C controller is used to interface with I2C devices
>> +at various speeds ranging from 100khz to 3.4Mhz.
>> +
>> +Required properties:
>> + - compatible: value should be.
>> + (a) "samsung,exynos5-hsi2c", for i2c compatible with exynos5 hsi2c.
>> + - reg: physical base address of the controller and length of memory mapped
>> + region.
>> + - interrupts: interrupt number to the cpu.
>> +
>> + - Samsung GPIO variant (deprecated):
>> + - gpios: The order of the gpios should be the following: <SDA, SCL>.
>> + The gpio specifier depends on the gpio controller.
>
> Huh? Why should we support a deprecated method with a new driver?
>
>> + - Pinctrl variant (preferred, if available):
>> + - pinctrl-0: Pin control group to be used for this controller.
>> + - pinctrl-names: Should contain only one value - "default".
>> +
>> +Optional properties:
>> + - samsung,hs-mode: Mode of operation, High speed or Fast speed mode. If not
>> + specified, default value is 0.
>> + - samsung,hs-clock-freq: Desired operating frequency in Hz of the bus.
>> + If not specified, the default value in Hz is 100000.
>> + - samsung,fs-clock-freq: Desired operarting frequency in Hz of the bus.
>> + If not specified, the default value in Hz is 100000.
>
> NACK! We have a generic binding for defining the bus speed. And
> shouldn't hs-mode be set depending on the bus speed?
>
>> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
>> index adfee98..9fbfa01 100644
>> --- a/drivers/i2c/busses/Kconfig
>> +++ b/drivers/i2c/busses/Kconfig
>> @@ -434,6 +434,13 @@ config I2C_EG20T
>> ML7213/ML7223/ML7831 is companion chip for Intel Atom E6xx series.
>> ML7213/ML7223/ML7831 is completely compatible for Intel EG20T PCH.
>>
>> +config I2C_EXYNOS5
>> + tristate "Exynos5 high-speed I2C driver"
>> + depends on ARCH_EXYNOS5 && OF
>> + help
>> + Say Y here to include support for High-speed I2C controller in the
>> + Exynos5 based Samsung SoCs.
>
> s/High/high/
>
>> +struct exynos5_i2c {
>> + struct i2c_adapter adap;
>> + unsigned int suspended:1;
>> +
>> + struct i2c_msg *msg;
>> + struct completion msg_complete;
>> + unsigned int msg_ptr;
>> + unsigned int msg_len;
>> +
>> + unsigned int irq;
>> +
>> + void __iomem *regs;
>> + struct clk *clk;
>> + struct device *dev;
>> + int state;
>> +
>> + /* GPIO lines for SDA/SCL*/
>> + int gpios[2];
>> +
>> + /* Controller operating frequency */
>> + unsigned int clock;
>> + unsigned int clk_cycle;
>> + unsigned int clk_div;
>> +
>> + /* HSI2C Controller can operate in
>> + * 1. High speed upto 3.4Mbps
>> + * 2. Fast speed upto 1Mbps
>> + */
>> + int speed_mode;
>> +};
>
> Only one space as indentation after the type, please.
Will change to 1 space for all of them
>
>> +
>> +static const struct of_device_id exynos5_i2c_match[] = {
>> + { .compatible = "samsung,exynos5-hsi2c" },
>> + {},
>> +};
>> +MODULE_DEVICE_TABLE(of, exynos5_i2c_match);
>> +
>> +static inline void exynos5_i2c_stop(struct exynos5_i2c *i2c)
>> +{
>> + writel(0, i2c->regs + HSI2C_INT_ENABLE);
>> +
>> + complete(&i2c->msg_complete);
>> +}
>
> I wonder if this needs to be a seperate function.
Initial patch used exynos5_i2c_stop function several times.
But, not its only once. Will remove
>
>> +
>> +static void exynos5_i2c_en_timeout(struct exynos5_i2c *i2c)
>> +{
>> + u32 i2c_timeout = readl(i2c->regs + HSI2C_TIMEOUT);
>> +
>> + /* Clear to enable Timeout */
>> + i2c_timeout &= ~HSI2C_TIMEOUT_EN;
>> + writel(i2c_timeout, i2c->regs + HSI2C_TIMEOUT);
>> +}
>> +
>> +static void exynos5_i2c_clr_pend_irq(struct exynos5_i2c *i2c)
>> +{
>> + /* Set these bits to clear them */
>
> Comment a bit obvious.
Shall i remove.
>
>> + writel(readl(i2c->regs + HSI2C_INT_STATUS),
>> + i2c->regs + HSI2C_INT_STATUS);
>> +
>> +}
>> +
>> +/* exynos5_i2c_clock_info: Calculates the clock divisor and
>> + * the clock cycle length (SCLK High + SCLK Low)
>> + *
>> + * Returns 0 on success, -EINVAL if the cycle length cannot
>> + * be calculated.
>> + */
>> +static int exynos5_i2c_clock_info(struct exynos5_i2c *i2c)
>> +{
>> + unsigned int op_clk = i2c->clock;
>> + unsigned int clkin = clk_get_rate(i2c->clk);
>> + unsigned int i, utemp0 = 0, utemp1 = 0;
>> + unsigned int t_ftl_cycle;
>> +
>> + /* FPCLK / FI2C =
>> + * (CLK_DIV + 1) * (TSCLK_L + TSCLK_H + 2) + 8 + 2 * FLT_CYCLE
>> + * utemp0 = (CLK_DIV + 1) * (TSCLK_L + TSCLK_H + 2)
>> + * utemp1 = (TSCLK_L + TSCLK_H + 2)
>> + */
>> + t_ftl_cycle = (readl(i2c->regs + HSI2C_CONF) >> 16) & 0x7;
>> + utemp0 = (clkin / op_clk) - 8 - 2 * t_ftl_cycle;
>> +
>> + /* CLK_DIV max is 256 */
>> + for (i = 0; i < 256; i++) {
>> + utemp1 = utemp0 / (i + 1);
>> +
>> + /* SCL_L and SCL_H each has max value of 255
>> + * Hence, For the clk_cycle to the have right value
>> + * utemp1 has to be less then 512 and more than 4.
>> + */
>> + if ((utemp1 < 512) && (utemp1 > 4)) {
>> + i2c->clk_cycle = utemp1 - 2;
>> + i2c->clk_div = i;
>> + return 0;
>> + }
>> + }
>> +
>> + dev_warn(i2c->dev, "%s: Wrong values for clock divisor and clock cycle,"
>> + "aborting\n", __func__);
>> + return -EINVAL;
>> +}
>> +
>> +/* exynos5_i2c_set_timing: updates the registers with appropriate
>> + * timing values calculated earlier (exynos5_i2c_clock_info)
>> + *
>> + * To handle the error case in calculates and to avoid the subsequent
>> + * calculates the clk_div and clk_cycle are stored
>> + */
>> +static void exynos5_i2c_set_timing(struct exynos5_i2c *i2c)
>> +{
>> + u32 i2c_timing_s1;
>> + u32 i2c_timing_s2;
>> + u32 i2c_timing_s3;
>> + u32 i2c_timing_sla;
>> + unsigned int n_clkdiv;
>> + unsigned int t_start_su, t_start_hd;
>> + unsigned int t_stop_su;
>> + unsigned int t_data_su, t_data_hd;
>> + unsigned int t_scl_l, t_scl_h;
>> + unsigned int t_sr_release;
>> +
>> + n_clkdiv = i2c->clk_div;
>> + t_scl_l = i2c->clk_cycle / 2;
>> + t_scl_h = i2c->clk_cycle / 2;
>> + t_start_su = t_scl_l;
>> + t_start_hd = t_scl_l;
>> + t_stop_su = t_scl_l;
>> + t_data_su = t_scl_l / 2;
>> + t_data_hd = t_scl_l / 2;
>> + t_sr_release = i2c->clk_cycle;
>> +
>> + i2c_timing_s1 = t_start_su << 24 | t_start_hd << 16 | t_stop_su << 8;
>> + i2c_timing_s2 = t_data_su << 24 | t_scl_l << 8 | t_scl_h << 0;
>> + i2c_timing_s3 = n_clkdiv << 16 | t_sr_release << 0;
>> + i2c_timing_sla = t_data_hd << 0;
>> +
>> + dev_dbg(i2c->dev, "tSTART_SU: %X, tSTART_HD: %X, tSTOP_SU: %X\n",
>> + t_start_su, t_start_hd, t_stop_su);
>> + dev_dbg(i2c->dev, "tDATA_SU: %X, tSCL_L: %X, tSCL_H: %X\n",
>> + t_data_su, t_scl_l, t_scl_h);
>> + dev_dbg(i2c->dev, "nClkDiv: %X, tSR_RELEASE: %X\n",
>> + n_clkdiv, t_sr_release);
>> + dev_dbg(i2c->dev, "tDATA_HD: %X\n", t_data_hd);
>> +
>> + if (i2c->speed_mode == HSI2C_HIGH_SPD) {
>> + writel(i2c_timing_s1, i2c->regs + HSI2C_TIMING_HS1);
>> + writel(i2c_timing_s2, i2c->regs + HSI2C_TIMING_HS2);
>> + writel(i2c_timing_s3, i2c->regs + HSI2C_TIMING_HS3);
>> + } else {
>> + writel(i2c_timing_s1, i2c->regs + HSI2C_TIMING_FS1);
>> + writel(i2c_timing_s2, i2c->regs + HSI2C_TIMING_FS2);
>> + writel(i2c_timing_s3, i2c->regs + HSI2C_TIMING_FS3);
>> + }
>> + writel(i2c_timing_sla, i2c->regs + HSI2C_TIMING_SLA);
>> +}
>> +
>> +/* exynos5_i2c_init: configures the controller for I2C functionality
>> + * Programs I2C controller for Master mode operation
>> + *
>> + * Note: Currently, supports AUTO mode of operation.
>> + */
>> +static void exynos5_i2c_init(struct exynos5_i2c *i2c)
>> +{
>> + u32 i2c_conf = readl(i2c->regs + HSI2C_CONF);
>> +
>> + writel((HSI2C_FUNC_MODE_I2C | HSI2C_MASTER),
>> + i2c->regs + HSI2C_CTL);
>> + writel(HSI2C_TRAILING_COUNT, i2c->regs + HSI2C_TRAILIG_CTL);
>> +
>> + exynos5_i2c_set_timing(i2c);
>> +
>> + if (i2c->speed_mode == HSI2C_HIGH_SPD)
>> + i2c_conf |= HSI2C_HS_MODE;
>> +
>> + writel(i2c_conf | HSI2C_AUTO_MODE, i2c->regs + HSI2C_CONF);
>> +}
>> +
>> +static void exynos5_i2c_reset(struct exynos5_i2c *i2c)
>> +{
>> + u32 i2c_ctl;
>> +
>> + /* Set and clear the bit for reset */
>> + i2c_ctl = readl(i2c->regs + HSI2C_CTL);
>> + i2c_ctl |= HSI2C_SW_RST;
>> + writel(i2c_ctl, i2c->regs + HSI2C_CTL);
>> +
>> + i2c_ctl = readl(i2c->regs + HSI2C_CTL);
>> + i2c_ctl &= ~HSI2C_SW_RST;
>> + writel(i2c_ctl, i2c->regs + HSI2C_CTL);
>> +
>> + /* Initialize the configure registers */
>> + exynos5_i2c_init(i2c);
>> +}
>> +
>> +static void exynos5_i2c_master_run(struct exynos5_i2c *i2c)
>> +{
>> + /* Start data transfer in Master mode */
>> + u32 i2c_auto_conf = readl(i2c->regs + HSI2C_AUTO_CONF);
>> + i2c_auto_conf |= HSI2C_MASTER_RUN;
>> + writel(i2c_auto_conf, i2c->regs + HSI2C_AUTO_CONF);
>> +}
>
> I wonder if this needs to be a seperate function.
This is to keep the functionality separate, but used only once.
Will remove.
>
>> +
>> +/* exynos5_i2c_irq: top level IRQ servicing routine
>> + *
>> + * INT_STATUS registers gives the interrupt details. Further,
>> + * FIFO_STATUS or TRANS_STATUS registers are to be check for detailed
>> + * state of the bus.
>> + */
>> +static irqreturn_t exynos5_i2c_irq(int irqno, void *dev_id)
>> +{
>> + struct exynos5_i2c *i2c = dev_id;
>> + u32 fifo_level, int_status, fifo_status, trans_status;
>> + unsigned char byte;
>> + int len = 0;
>> +
>> + i2c->state = -EINVAL;
>> +
>> + int_status = readl(i2c->regs + HSI2C_INT_STATUS);
>> + fifo_status = readl(i2c->regs + HSI2C_FIFO_STATUS);
>> +
>> + if (int_status & HSI2C_INT_I2C) {
>> + trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS);
>> + if (trans_status & HSI2C_NO_DEV_ACK) {
>> + dev_dbg(i2c->dev, "No ACK from device\n");
>> + i2c->state = -ENXIO;
>> + } else if (trans_status & HSI2C_NO_DEV) {
>> + dev_dbg(i2c->dev, "No device\n");
>> + i2c->state = -ENXIO;
>> + } else if (trans_status & HSI2C_TRANS_ABORT) {
>> + dev_dbg(i2c->dev, "Deal with arbitration lose\n");
>> + i2c->state = -EAGAIN;
>> + } else if (trans_status & HSI2C_TIMEOUT_AUTO) {
>> + dev_dbg(i2c->dev, "Accessing device timed out\n");
>> + i2c->state = -EAGAIN;
>> + }
>> + }
>> + /* TX_ALMOSTEMPTY can happen along with HSI2C_INT_I2C */
>> + else if (int_status &
>> + (HSI2C_INT_TX_UNDERRUN | HSI2C_INT_TX_ALMOSTEMPTY)) {
>> + fifo_level = HSI2C_TX_FIFO_LVL(fifo_status);
>> +
>> + /* To support probing the devices for detection */
>> + if (i2c->msg->len == 0) {
>> + i2c->state = -ENXIO;
>> + goto stop;
>> + }
>> +
>> + /* 0x30 is the default trigger level for TX FIFO */
>> + len = 48 - fifo_level;
>> +
>> + if (len > i2c->msg->len)
>> + len = i2c->msg->len;
>> +
>> + i2c->msg_len += len;
>> + while (len > 0) {
>> + byte = i2c->msg->buf[i2c->msg_ptr++];
>> + writel(byte, i2c->regs + HSI2C_TX_DATA);
>> + len--;
>> + }
>> + i2c->state = 0;
>> + goto stop;
>> + }
>> + /* If TX FIFO is full (give chance to clear) */
>> + else if (int_status & HSI2C_INT_TX_OVERRUN)
>> + i2c->state = 0;
>> +
>> + if (int_status & (HSI2C_INT_RX_OVERRUN | HSI2C_INT_TRAILING |
>> + HSI2C_INT_RX_UNDERRUN | HSI2C_INT_RX_ALMOSTFULL)) {
>> + fifo_level = HSI2C_RX_FIFO_LVL(fifo_status);
>> +
>> + if (fifo_level >= i2c->msg->len)
>> + len = i2c->msg->len;
>> + else
>> + len = fifo_level;
>> +
>> + i2c->msg_len += len;
>> + while (len > 0) {
>> + byte = (unsigned char)
>> + readl(i2c->regs + HSI2C_RX_DATA);
>> + i2c->msg->buf[i2c->msg_ptr++] = byte;
>> + len--;
>> + }
>> + i2c->state = 0;
>> + }
>> +
>> +
>> + stop:
>> + if ((i2c->msg_len == i2c->msg->len) || (i2c->state < 0))
>> + exynos5_i2c_stop(i2c);
>> +
>> + exynos5_i2c_clr_pend_irq(i2c);
>> +
>> + return IRQ_HANDLED;
>> +}
>> +
>> +/*
>> + * exynos5_i2c_wait_bus_idle
>> + *
>> + * Check for Master Busy bit in Trans status register
>> + * Loop for a while if set.
>> + *
>> + * Returns -EBUSY if the bus cannot be bought to idle
>> + */
>> +static int exynos5_i2c_wait_bus_idle(struct exynos5_i2c *i2c)
>> +{
>> + unsigned long stop_time;
>> + u32 trans_status;
>> +
>> + /* wait for 100 milli seconds for the bus to be idle */
>> + stop_time = jiffies + msecs_to_jiffies(100) + 1;
>> + do {
>> + trans_status = readl(i2c->regs + HSI2C_TRANS_STATUS);
>> + /* Return if the bus turns idle */
>> + if (!(trans_status & HSI2C_MASTER_BUSY))
>> + return 0;
>> +
>> + usleep_range(50, 200);
>> + } while (time_before(jiffies, stop_time));
>> +
>> + return -EBUSY;
>> +}
>> +
>> +/*
>> + * exynos5_i2c_message_start: Configures the bus and starts the xfer
>> + * i2c: struct exynos5_i2c pointer for the current bus
>> + * stop: Enables stop after transfer if set. Set for last transfer of
>> + * in the list of messages.
>> + *
>> + * Configures the bus for read/write function
>> + * Sets chip address to talk to, message length to be sent.
>> + * Enables appropriate interrupts and sends start xfer command.
>> + */
>> +static void exynos5_i2c_message_start(struct exynos5_i2c *i2c, int stop)
>> +{
>> + u32 i2c_ctl;
>> + u32 int_en = HSI2C_INT_I2C_EN;
>> + u32 i2c_auto_conf = 0;
>> + u32 fifo_ctl;
>> +
>> + exynos5_i2c_en_timeout(i2c);
>> +
>> + fifo_ctl = HSI2C_RXFIFO_EN | HSI2C_TXFIFO_EN |
>> + HSI2C_TXFIFO_TRIGGER_LEVEL | HSI2C_RXFIFO_TRIGGER_LEVEL;
>> + writel(fifo_ctl, i2c->regs + HSI2C_FIFO_CTL);
>> +
>> + i2c_ctl = readl(i2c->regs + HSI2C_CTL);
>> + i2c_ctl &= ~(HSI2C_TXCHON | HSI2C_RXCHON);
>> +
>> + if (i2c->msg->flags & I2C_M_RD) {
>> + i2c_ctl |= HSI2C_RXCHON;
>> +
>> + i2c_auto_conf |= HSI2C_READ_WRITE;
>> +
>> + int_en |= (HSI2C_INT_RX_ALMOSTFULL_EN |
>> + HSI2C_INT_TRAILING_EN);
>> + } else {
>> + i2c_ctl |= HSI2C_TXCHON;
>> +
>> + int_en |= HSI2C_INT_TX_ALMOSTEMPTY_EN;
>> + }
>> +
>> + if (stop == 1)
>> + i2c_auto_conf |= HSI2C_STOP_AFTER_TRANS;
>> +
>> + writel(HSI2C_SLV_ADDR_MAS(i2c->msg->addr), i2c->regs + HSI2C_ADDR);
>> +
>> + writel(i2c_ctl, i2c->regs + HSI2C_CTL);
>> +
>> + /* In auto mode the length of xfer cannot be 0 */
>> + if (i2c->msg->len == 0)
>> + i2c_auto_conf |= 0x1;
>
> So you send some byte then? Why not reject the message?
This is to support the probing the devices (i2cdetect cases)

>
>> + else
>> + i2c_auto_conf |= i2c->msg->len;
>> +
>> + writel(i2c_auto_conf, i2c->regs + HSI2C_AUTO_CONF);
>> +
>> + exynos5_i2c_master_run(i2c);
>> +
>> + writel(int_en, i2c->regs + HSI2C_INT_ENABLE);
>> +}
>> +
>> +static int exynos5_i2c_xfer_msg(struct exynos5_i2c *i2c,
>> + struct i2c_msg *msgs, int stop)
>> +{
>> + unsigned long timeout;
>> + int ret;
>> +
>> + i2c->msg = msgs;
>> + i2c->msg_ptr = 0;
>> + i2c->msg_len = 0;
>> +
>> + INIT_COMPLETION(i2c->msg_complete);
>> +
>> + exynos5_i2c_message_start(i2c, stop);
>> +
>> + ret = wait_for_completion_interruptible_timeout
>> + (&i2c->msg_complete, EXYNOS5_I2C_TIMEOUT);
>
> interruptible? Have you checked SIGINT works properly? It often causes
> problems with I2C drivers.
Not tested much, will do.
>
>> + if (ret >= 0)
>> + timeout = ret;
>> + else
>> + return ret;
>> +
>> + ret = i2c->state;
>> +
>> + if ((timeout == 0) || (ret < 0)) {
>> + exynos5_i2c_reset(i2c);
>> + if (timeout == 0) {
>> + dev_warn(i2c->dev, "%s timeout\n",
>> + (msgs->flags & I2C_M_RD) ? "rx" : "tx");
>> + return ret;
>> + } else if (ret == -EAGAIN) {
>> + return ret;
>> + }
>> + }
>> +
>> + /*
>> + * If this is the last message to be transfered (stop == 1)
>> + * Then check if the bus can be brought back to idle.
>> + *
>> + * Return -EBUSY if the bus still busy.
>> + */
>> + if (stop && exynos5_i2c_wait_bus_idle(i2c))
>> + return -EBUSY;
>> +
>> + /* Return the state as in interrupt routine */
>> + return ret;
>> +}
>> +
>> +static int exynos5_i2c_xfer(struct i2c_adapter *adap,
>> + struct i2c_msg *msgs, int num)
>> +{
>> + struct exynos5_i2c *i2c = (struct exynos5_i2c *)adap->algo_data;
>> + struct i2c_msg *msgs_ptr = msgs;
>> + int retry, i = 0;
>> + int ret = 0, ret_pm;
>> + int stop = 0;
>> +
>> + if (i2c->suspended) {
>> + dev_err(i2c->dev, "HS-I2C is not initialzed.\n");
>> + return -EIO;
>> + }
>> +
>> + ret_pm = pm_runtime_get_sync(i2c->dev);
>> + if (IS_ERR_VALUE(ret_pm)) {
>> + ret = -EIO;
>> + goto out;
>> + }
>> +
>> + clk_prepare_enable(i2c->clk);
>> +
>> + for (retry = 0; retry < adap->retries; retry++) {
>> + for (i = 0; i < num; i++) {
>> + stop = (i == num - 1);
>> +
>> + ret = exynos5_i2c_xfer_msg(i2c, msgs_ptr, stop);
>> + msgs_ptr++;
>> +
>> + if (ret == -EAGAIN) {
>> + msgs_ptr = msgs;
>> + break;
>> + } else if (ret < 0) {
>> + goto out;
>> + }
>> + }
>> +
>> + if ((i == num) && (ret != -EAGAIN))
>> + break;
>> +
>> + dev_dbg(i2c->dev, "retrying transfer (%d)\n", retry);
>> +
>> + udelay(100);
>> + }
>> +
>> + if (i == num) {
>> + /* only one message, return number of bytes transfered */
>> + if (num == 1)
>> + ret = i2c->msg_len;
>> + else
>> + ret = num;
>> + } else {
>> + /* Only one message, cannot access the device */
>> + if (i == 1)
>> + ret = -EREMOTEIO;
>> + else
>> + ret = i;
>> +
>> + dev_warn(i2c->dev, "xfer message failed\n");
>> + }
>> +
>> + out:
>> + clk_disable_unprepare(i2c->clk);
>> + pm_runtime_mark_last_busy(i2c->dev);
>> + pm_runtime_put_autosuspend(i2c->dev);
>> + return ret;
>> +}
>> +
>> +static u32 exynos5_i2c_func(struct i2c_adapter *adap)
>> +{
>> + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
>
> Have you checked SMBUS_QUICK works (with i2cdetect for example)?
i2cdetect is working fine now.
>
>> +}
>> +
>> +static const struct i2c_algorithm exynos5_i2c_algorithm = {
>> + .master_xfer = exynos5_i2c_xfer,
>> + .functionality = exynos5_i2c_func,
>> +};
>> +
>> +/**
>> + * Parse a list of GPIOs from a node property and request each one
>> + *
>> + * @param i2c i2c driver data
>> + * @return 0 on success, -EINVAL on error, in which case no GPIOs requested
>> +*/
>> +static int exynos5_i2c_parse_dt_gpio(struct exynos5_i2c *i2c)
>> +{
>> + int idx, gpio, ret;
>> +
>> + for (idx = 0; idx < 2; idx++) {
>> + gpio = of_get_gpio(i2c->dev->of_node, idx);
>> + if (!gpio_is_valid(gpio)) {
>> + dev_err(i2c->dev, "invalid gpio[%d]: %d\n", idx, gpio);
>> + return -EINVAL;
>> + }
>> + i2c->gpios[idx] = gpio;
>> +
>> + ret = devm_gpio_request(i2c->dev, gpio, "i2c-bus");
>> + if (ret) {
>> + dev_err(i2c->dev, "gpio [%d] request failed\n", gpio);
>> + return -EINVAL;
>> + }
>> + }
>> + return 0;
>> +}
>> +
>> +#define HSI2C_REG(regname) {.name = #regname, .offset = regname}
>> +static struct debugfs_reg32 exynos5_hsi2c_regs[] = {
>> + HSI2C_REG(HSI2C_CTL), HSI2C_REG(HSI2C_FIFO_CTL),
>> + HSI2C_REG(HSI2C_TRAILIG_CTL), HSI2C_REG(HSI2C_CLK_CTL),
>> + HSI2C_REG(HSI2C_CLK_SLOT), HSI2C_REG(HSI2C_INT_ENABLE),
>> + HSI2C_REG(HSI2C_INT_STATUS), HSI2C_REG(HSI2C_ERR_STATUS),
>> + HSI2C_REG(HSI2C_FIFO_STATUS), HSI2C_REG(HSI2C_TX_DATA),
>> + HSI2C_REG(HSI2C_RX_DATA), HSI2C_REG(HSI2C_CONF),
>> + HSI2C_REG(HSI2C_AUTO_CONF), HSI2C_REG(HSI2C_TIMEOUT),
>> + HSI2C_REG(HSI2C_MANUAL_CMD), HSI2C_REG(HSI2C_TRANS_STATUS),
>> + HSI2C_REG(HSI2C_TIMING_HS1), HSI2C_REG(HSI2C_TIMING_HS2),
>> + HSI2C_REG(HSI2C_TIMING_HS3), HSI2C_REG(HSI2C_TIMING_FS1),
>> + HSI2C_REG(HSI2C_TIMING_FS2), HSI2C_REG(HSI2C_TIMING_FS3),
>> + HSI2C_REG(HSI2C_TIMING_SLA), HSI2C_REG(HSI2C_ADDR),
>> +};
>> +
>> +static struct debugfs_regset32 exynos5_hsi2c_regset = {
>> + .regs = exynos5_hsi2c_regs,
>> + .nregs = ARRAY_SIZE(exynos5_hsi2c_regs),
>> +};
>> +
>> +static struct dentry *exynos5_hsi2c_reg_debugfs;
>> +
>> +static int exynos5_i2c_probe(struct platform_device *pdev)
>> +{
>> + struct device_node *np = pdev->dev.of_node;
>> + struct exynos5_i2c *i2c;
>> + int ret;
>> +
>> + if (!np) {
>> + dev_err(&pdev->dev, "no device node\n");
>> + return -ENOENT;
>> + }
>> +
>> + i2c = devm_kzalloc(&pdev->dev, sizeof(struct exynos5_i2c), GFP_KERNEL);
>> + if (!i2c) {
>> + dev_err(&pdev->dev, "no memory for state\n");
>> + return -ENOMEM;
>> + }
>> +
>> + /* Mode of operation High/Fast Speed mode */
>> + if (of_get_property(np, "samsung,hs-mode", NULL)) {
>> + i2c->speed_mode = 1;
>> + if (of_property_read_u32(np, "samsung,hs-clock", &i2c->clock))
>> + i2c->clock = HSI2C_HS_TX_CLOCK;
>> + } else {
>> + i2c->speed_mode = 0;
>> + if (of_property_read_u32(np, "samsung,fs-clock", &i2c->clock))
>> + i2c->clock = HSI2C_FS_TX_CLOCK;
>> + }
>> +
>> + strlcpy(i2c->adap.name, "exynos5-i2c", sizeof(i2c->adap.name));
>> + i2c->adap.owner = THIS_MODULE;
>> + i2c->adap.algo = &exynos5_i2c_algorithm;
>> + i2c->adap.retries = 2;
>> + i2c->adap.class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
>> +
>> + i2c->dev = &pdev->dev;
>> + i2c->clk = devm_clk_get(&pdev->dev, "hsi2c");
>> + if (IS_ERR(i2c->clk)) {
>> + dev_err(&pdev->dev, "cannot get clock\n");
>> + return -ENOENT;
>> + }
>> +
>> + clk_prepare_enable(i2c->clk);
>
> devm_*? Quite a few drivers have been converted to devm_* recently.
> Check them as a guideline.
>
>> +
>> + i2c->regs = of_iomap(np, 0);
>
> devm_ioremap_resource()
This was a comment from Thomas on v1.
https://lkml.org/lkml/2012/11/27/264

Kindly, suggest me which one is more optimal in this case.
>
>> + if (!i2c->regs) {
>> + dev_err(&pdev->dev, "cannot map HS-I2C IO\n");
>> + ret = -EADDRNOTAVAIL;
>> + goto err_clk;
>> + }
>> +
>> + i2c->adap.algo_data = i2c;
>> + i2c->adap.dev.parent = &pdev->dev;
>> +
>> + /* parse device tree and inititalise the gpio */
>> + ret = exynos5_i2c_parse_dt_gpio(i2c);
>> + if (ret)
>> + goto err_clk;
>> +
>> + /* Clear pending interrupts from u-boot or misc causes */
>> + exynos5_i2c_clr_pend_irq(i2c);
>> +
>> + ret = exynos5_i2c_clock_info(i2c);
>> + if (ret)
>> + goto err_iomap;
>> +
>> + exynos5_i2c_init(i2c);
>> +
>> + init_completion(&i2c->msg_complete);
>> +
>> + i2c->irq = ret = irq_of_parse_and_map(np, 0);
>> + if (ret <= 0) {
>> + dev_err(&pdev->dev, "cannot find HS-I2C IRQ\n");
>> + ret = -EINVAL;
>> + goto err_iomap;
>> + }
>> +
>> + ret = devm_request_irq(&pdev->dev, i2c->irq, exynos5_i2c_irq,
>> + 0, dev_name(&pdev->dev), i2c);
>> +
>> + if (ret != 0) {
>> + dev_err(&pdev->dev, "cannot request HS-I2C IRQ %d\n", i2c->irq);
>> + goto err_iomap;
>> + }
>> +
>> + /*
>> + * TODO: Use private lock to avoid race conditions as
>> + * mentioned in pm_runtime.txt
>> + */
>> + pm_runtime_enable(i2c->dev);
>> + pm_runtime_set_autosuspend_delay(i2c->dev, EXYNOS5_I2C_PM_TIMEOUT);
>> + pm_runtime_use_autosuspend(i2c->dev);
>> +
>> + ret = pm_runtime_get_sync(i2c->dev);
>> + if (IS_ERR_VALUE(ret))
>> + goto err_iomap;
>> +
>> + i2c->adap.nr = -1;
>
> core will set this (patch is in -next)
Right.
>
>> + i2c->adap.dev.of_node = np;
>> +
>> + ret = i2c_add_numbered_adapter(&i2c->adap);
>> + if (ret < 0) {
>> + dev_err(&pdev->dev, "failed to add bus to i2c core\n");
>> + goto err_pm;
>> + }
>> +
>> + of_i2c_register_devices(&i2c->adap);
>> + platform_set_drvdata(pdev, i2c);
>> +
>> + exynos5_hsi2c_reg_debugfs = debugfs_create_regset32("exynos5-hsi2c",
>> + S_IFREG | S_IRUGO,
>> + NULL, &exynos5_hsi2c_regset);
>> + if (!exynos5_hsi2c_reg_debugfs)
>> + dev_warn(&pdev->dev, "failed to create debugfs entries,"
>> + "but will continue.");
>> +
>> + clk_disable_unprepare(i2c->clk);
>> + pm_runtime_mark_last_busy(i2c->dev);
>> + pm_runtime_put_autosuspend(i2c->dev);
>> +
>> + return 0;
>> +
>> + err_pm:
>> + pm_runtime_put(i2c->dev);
>> + pm_runtime_disable(&pdev->dev);
>> + err_iomap:
>> + iounmap(i2c->regs);
>> + err_clk:
>> + clk_disable_unprepare(i2c->clk);
>> + return ret;
>> +}
>> +
>> +static int exynos5_i2c_remove(struct platform_device *pdev)
>> +{
>> + struct exynos5_i2c *i2c = platform_get_drvdata(pdev);
>> + int ret;
>> +
>> + ret = pm_runtime_get_sync(&pdev->dev);
>> + if (IS_ERR_VALUE(ret))
>> + return ret;
>> +
>> + i2c_del_adapter(&i2c->adap);
>> +
>> + pm_runtime_put(&pdev->dev);
>> + pm_runtime_disable(&pdev->dev);
>> +
>> + iounmap(i2c->regs);
>> + clk_disable_unprepare(i2c->clk);
>> +
>> + if (exynos5_hsi2c_reg_debugfs)
>> + debugfs_remove(exynos5_hsi2c_reg_debugfs);
>> +
>> + return 0;
>> +}
>> +
>> +#ifdef CONFIG_PM
>> +static int exynos5_i2c_suspend_noirq(struct device *dev)
>> +{
>> + struct platform_device *pdev = to_platform_device(dev);
>> + struct exynos5_i2c *i2c = platform_get_drvdata(pdev);
>> +
>> + i2c->suspended = 1;
>> +
>> + return 0;
>> +}
>> +
>> +static int exynos5_i2c_resume_noirq(struct device *dev)
>> +{
>> + struct platform_device *pdev = to_platform_device(dev);
>> + struct exynos5_i2c *i2c = platform_get_drvdata(pdev);
>> + int ret = 0;
>> +
>> + clk_prepare_enable(i2c->clk);
>> +
>> + ret = exynos5_i2c_clock_info(i2c);
>> + if (ret) {
>> + clk_disable_unprepare(i2c->clk);
>> + return ret;
>> + }
>> +
>> + exynos5_i2c_init(i2c);
>> + clk_disable_unprepare(i2c->clk);
>> + i2c->suspended = 0;
>> +
>> + return 0;
>> +}
>> +
>> +static const struct dev_pm_ops exynos5_i2c_dev_pm_ops = {
>> + .suspend_noirq = exynos5_i2c_suspend_noirq,
>> + .resume_noirq = exynos5_i2c_resume_noirq,
>> +};
>> +
>> +#define EXYNOS5_DEV_PM_OPS (&exynos5_i2c_dev_pm_ops)
>> +#else
>> +#define EXYNOS5_DEV_PM_OPS NULL
>> +#endif
>> +
>> +static struct platform_driver exynos5_i2c_driver = {
>> + .probe = exynos5_i2c_probe,
>> + .remove = exynos5_i2c_remove,
>> + .driver = {
>> + .owner = THIS_MODULE,
>> + .name = "exynos5-hsi2c",
>> + .pm = EXYNOS5_DEV_PM_OPS,
>> + .of_match_table = exynos5_i2c_match,
>> + },
>> +};
>> +
>> +static int __init i2c_adap_exynos5_init(void)
>> +{
>> + return platform_driver_register(&exynos5_i2c_driver);
>> +}
>> +subsys_initcall(i2c_adap_exynos5_init);
>> +
>> +static void __exit i2c_adap_exynos5_exit(void)
>> +{
>> + platform_driver_unregister(&exynos5_i2c_driver);
>> +}
>> +module_exit(i2c_adap_exynos5_exit);
>> +
>> +MODULE_DESCRIPTION("Exynos5 HS-I2C Bus driver");
>> +MODULE_AUTHOR("Naveen Krishna Chatradhi, <ch.naveen@samsung.com>");
>> +MODULE_AUTHOR("Taekgyun Ko, <taeggyun.ko@samsung.com>");
>> +MODULE_LICENSE("GPL");
>
> Header says GPL v2
>
> Also, quite some dev_dbgs in here. I haven't made up my mind yet if all
> are needed, but maybe you can already check if you want to insist on all
> of them.
>
> Since you need to resend anyway, can you fold the patch from Yuvaraj
> Kumar C D into the driver if it makes sense to you?
Sure, I've discussed with Yuvaraj on this, I will incorportate his changes and
https://patchwork.kernel.org/patch/2464681/ and
https://patchwork.kernel.org/patch/2420351/

in the next revision.

>
> Thanks,
>
> Wolfram
Thanks for your valuable time and comments

--
Shine bright,
(: Nav :)