i2c-stu300: I2C STU300 stability updates

- blk clk is enabled when an irq arrives. The clk should be enabled,
  but just to make sure.
- All error bits are handled no matter state machine state
- All irq's will run complete() except for irq's that wasn't an event.
- No more looking into status registers just in case an interrupt
  has happend and the irq handle wasn't executed.
- irq_disable/enable are now separete functions.
- clk settings calculation changed to round upwards instead of
  downwards.
- Number of address send attempts before giving up is increased to 12
  from 10 since it most times take 8 tries before getting through.

Signed-off-by: Linus Walleij <linus.walleij@stericsson.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>

1 files changed, 92 insertions, 65 deletions

diff --git a/drivers/i2c/busses/i2c-stu300.c b/drivers/i2c/busses/i2c-stu300.c
index 182e711318ba..d2728a28a8db 100644
--- a/drivers/i2c/busses/i2c-stu300.c
+++ b/drivers/i2c/busses/i2c-stu300.c
@@ -117,7 +117,8 @@ enum stu300_error {
         STU300_ERROR_NONE = 0,
         STU300_ERROR_ACKNOWLEDGE_FAILURE,
         STU300_ERROR_BUS_ERROR,
-        STU300_ERROR_ARBITRATION_LOST
+        STU300_ERROR_ARBITRATION_LOST,
+        STU300_ERROR_UNKNOWN
 };
 
 /* timeout waiting for the controller to respond */
@@ -127,7 +128,7 @@ enum stu300_error {
  * 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
+#define NUM_ADDR_RESEND_ATTEMPTS 12
 
 /* I2C clock speed, in Hz 0-400kHz*/
 static unsigned int scl_frequency = 100000;
@@ -149,6 +150,7 @@ module_param(scl_frequency, uint,  0644);
  * @msg_index: index of current message
  * @msg_len: length of current message
  */
+
 struct stu300_dev {
         struct platform_device  *pdev;
         struct i2c_adapter      adapter;
@@ -188,6 +190,27 @@ static inline u32 stu300_r8(void __iomem *address)
         return readl(address) & 0x000000FFU;
 }
 
+static void stu300_irq_enable(struct stu300_dev *dev)
+{
+        u32 val;
+        val = stu300_r8(dev->virtbase + I2C_CR);
+        val |= I2C_CR_INTERRUPT_ENABLE;
+        /* Twice paranoia (possible HW glitch) */
+        stu300_wr8(val, dev->virtbase + I2C_CR);
+        stu300_wr8(val, dev->virtbase + I2C_CR);
+}
+
+static void stu300_irq_disable(struct stu300_dev *dev)
+{
+        u32 val;
+        val = stu300_r8(dev->virtbase + I2C_CR);
+        val &= ~I2C_CR_INTERRUPT_ENABLE;
+        /* Twice paranoia (possible HW glitch) */
+        stu300_wr8(val, dev->virtbase + I2C_CR);
+        stu300_wr8(val, dev->virtbase + I2C_CR);
+}
+
+
 /*
  * Tells whether a certain event or events occurred in
  * response to a command. The events represent states in
@@ -196,9 +219,10 @@ static inline u32 stu300_r8(void __iomem *address)
  * documentation and can only be treated as abstract state
  * machine states.
  *
- * @ret 0 = event has not occurred, any other value means
- * the event occurred.
+ * @ret 0 = event has not occurred or unknown error, any
+ * other value means the correct event occurred or an error.
  */
+
 static int stu300_event_occurred(struct stu300_dev *dev,
                                    enum stu300_event mr_event) {
         u32 status1;
@@ -206,11 +230,28 @@ static int stu300_event_occurred(struct stu300_dev *dev,
 
         /* 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);
 
+        /* Block any multiple interrupts */
+        stu300_irq_disable(dev);
+
+        /* Check for errors first */
+        if (status2 & I2C_SR2_AF_IND) {
+                dev->cmd_err = STU300_ERROR_ACKNOWLEDGE_FAILURE;
+                return 1;
+        } else if (status2 & I2C_SR2_BERR_IND) {
+                dev->cmd_err = STU300_ERROR_BUS_ERROR;
+                return 1;
+        } else if (status2 & I2C_SR2_ARLO_IND) {
+                dev->cmd_err = STU300_ERROR_ARBITRATION_LOST;
+                return 1;
+        }
+
         switch (mr_event) {
         case STU300_EVENT_1:
                 if (status1 & I2C_SR1_ADSL_IND)
@@ -221,10 +262,6 @@ static int stu300_event_occurred(struct stu300_dev *dev,
         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;
@@ -240,8 +277,6 @@ static int stu300_event_occurred(struct stu300_dev *dev,
         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;
@@ -252,8 +287,15 @@ static int stu300_event_occurred(struct stu300_dev *dev,
         default:
                 break;
         }
-        if (status2 & I2C_SR2_ARLO_IND)
-                dev->cmd_err = STU300_ERROR_ARBITRATION_LOST;
+        /* If we get here, we're on thin ice.
+         * Here we are in a status where we have
+         * gotten a response that does not match
+         * what we requested.
+         */
+        dev->cmd_err = STU300_ERROR_UNKNOWN;
+        dev_err(&dev->pdev->dev,
+                "Unhandled interrupt! %d sr1: 0x%x sr2: 0x%x\n",
+                mr_event, status1, status2);
         return 0;
 }
 
@@ -262,21 +304,20 @@ static irqreturn_t stu300_irh(int irq, void *data)
         struct stu300_dev *dev = data;
         int res;
 
+        /* Just make sure that the block is clocked */
+        clk_enable(dev->clk);
+
         /* 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);
-                }
-        }
+
+        res = stu300_event_occurred(dev, dev->cmd_event);
+        if (res || dev->cmd_err != STU300_ERROR_NONE)
+                complete(&dev->cmd_complete);
+
         spin_unlock(&dev->cmd_issue_lock);
+
+        clk_disable(dev->clk);
+
         return IRQ_HANDLED;
 }
 
@@ -308,7 +349,6 @@ static int stu300_start_and_await_event(struct stu300_dev *dev,
         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() "
@@ -342,7 +382,6 @@ 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. */
@@ -354,36 +393,18 @@ static int stu300_await_event(struct stu300_dev *dev,
         /* 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);
+        init_completion(&dev->cmd_complete);
 
-        /* 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;
-        }
+        /* Turn on the I2C interrupt for current operation */
+        stu300_irq_enable(dev);
 
         /* 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()"
@@ -401,7 +422,6 @@ static int stu300_await_event(struct stu300_dev *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 "
@@ -457,18 +477,19 @@ struct stu300_clkset {
 };
 
 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 },
+        { 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)
 {
 
@@ -494,10 +515,10 @@ static int stu300_set_clk(struct stu300_dev *dev, unsigned long clkrate)
 
         if (dev->speed > 100000)
                 /* Fast Mode I2C */
-                val = ((clkrate/dev->speed)-9)/3;
+                val = ((clkrate/dev->speed) - 9)/3 + 1;
         else
                 /* Standard Mode I2C */
-                val = ((clkrate/dev->speed)-7)/2;
+                val = ((clkrate/dev->speed) - 7)/2 + 1;
 
         /* According to spec the divider must be > 2 */
         if (val < 0x002) {
@@ -557,6 +578,7 @@ static int stu300_init_hw(struct stu300_dev *dev)
          */
         clkrate = clk_get_rate(dev->clk);
         ret = stu300_set_clk(dev, clkrate);
+
         if (ret)
                 return ret;
         /*
@@ -641,7 +663,6 @@ static int stu300_xfer_msg(struct i2c_adapter *adap,
         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. */
@@ -715,14 +736,15 @@ static int stu300_xfer_msg(struct i2c_adapter *adap,
 
         if (attempts < NUM_ADDR_RESEND_ATTEMPTS && attempts > 0) {
                 dev_dbg(&dev->pdev->dev, "managed to get address "
-                       "through after %d attempts\n", attempts);
+                        "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);
+                        "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++) {
@@ -804,8 +826,10 @@ static int stu300_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 {
         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,
@@ -817,6 +841,7 @@ static int stu300_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
                 dev->msg_index = i;
 
                 ret = stu300_xfer_msg(adap, &msgs[i], (i == (num - 1)));
+
                 if (ret != 0) {
                         num = ret;
                         break;
@@ -845,6 +870,7 @@ stu300_probe(struct platform_device *pdev)
         struct resource *res;
         int bus_nr;
         int ret = 0;
+        char clk_name[] = "I2C0";
 
         dev = kzalloc(sizeof(struct stu300_dev), GFP_KERNEL);
         if (!dev) {
@@ -854,7 +880,8 @@ stu300_probe(struct platform_device *pdev)
         }
 
         bus_nr = pdev->id;
-        dev->clk = clk_get(&pdev->dev, NULL);
+        clk_name[3] += (char)bus_nr;
+        dev->clk = clk_get(&pdev->dev, clk_name);
         if (IS_ERR(dev->clk)) {
                 ret = PTR_ERR(dev->clk);
                 dev_err(&pdev->dev, "could not retrieve i2c bus clock\n");