1 files changed, 53 insertions, 4 deletions

diff --git a/drivers/i2c/busses/i2c-davinci.c b/drivers/i2c/busses/i2c-davinci.c
index 352b4e7bdd9e..2222c87876b9 100644
--- a/drivers/i2c/busses/i2c-davinci.c
+++ b/drivers/i2c/busses/i2c-davinci.c
@@ -37,6 +37,7 @@
 #include <linux/io.h>
 #include <linux/slab.h>
 #include <linux/cpufreq.h>
+#include <linux/gpio.h>
 
 #include <mach/hardware.h>
 #include <mach/i2c.h>
@@ -44,6 +45,7 @@
 /* ----- global defines ----------------------------------------------- */
 
 #define DAVINCI_I2C_TIMEOUT     (1*HZ)
+#define DAVINCI_I2C_MAX_TRIES   2
 #define I2C_DAVINCI_INTR_ALL    (DAVINCI_I2C_IMR_AAS | \
                                  DAVINCI_I2C_IMR_SCD | \
                                  DAVINCI_I2C_IMR_ARDY | \
@@ -131,6 +133,44 @@ static inline u16 davinci_i2c_read_reg(struct davinci_i2c_dev *i2c_dev, int reg)
         return __raw_readw(i2c_dev->base + reg);
 }
 
+/* Generate a pulse on the i2c clock pin. */
+static void generic_i2c_clock_pulse(unsigned int scl_pin)
+{
+        u16 i;
+
+        if (scl_pin) {
+                /* Send high and low on the SCL line */
+                for (i = 0; i < 9; i++) {
+                        gpio_set_value(scl_pin, 0);
+                        udelay(20);
+                        gpio_set_value(scl_pin, 1);
+                        udelay(20);
+                }
+        }
+}
+
+/* This routine does i2c bus recovery as specified in the
+ * i2c protocol Rev. 03 section 3.16 titled "Bus clear"
+ */
+static void i2c_recover_bus(struct davinci_i2c_dev *dev)
+{
+        u32 flag = 0;
+        struct davinci_i2c_platform_data *pdata = dev->dev->platform_data;
+
+        dev_err(dev->dev, "initiating i2c bus recovery\n");
+        /* Send NACK to the slave */
+        flag = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG);
+        flag |=  DAVINCI_I2C_MDR_NACK;
+        /* write the data into mode register */
+        davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, flag);
+        if (pdata)
+                generic_i2c_clock_pulse(pdata->scl_pin);
+        /* Send STOP */
+        flag = davinci_i2c_read_reg(dev, DAVINCI_I2C_MDR_REG);
+        flag |= DAVINCI_I2C_MDR_STP;
+        davinci_i2c_write_reg(dev, DAVINCI_I2C_MDR_REG, flag);
+}
+
 static inline void davinci_i2c_reset_ctrl(struct davinci_i2c_dev *i2c_dev,
                                                                 int val)
 {
@@ -236,14 +276,22 @@ static int i2c_davinci_wait_bus_not_busy(struct davinci_i2c_dev *dev,
                                          char allow_sleep)
 {
         unsigned long timeout;
+        static u16 to_cnt;
 
         timeout = jiffies + dev->adapter.timeout;
         while (davinci_i2c_read_reg(dev, DAVINCI_I2C_STR_REG)
                & DAVINCI_I2C_STR_BB) {
-                if (time_after(jiffies, timeout)) {
-                        dev_warn(dev->dev,
-                                 "timeout waiting for bus ready\n");
-                        return -ETIMEDOUT;
+                if (to_cnt <= DAVINCI_I2C_MAX_TRIES) {
+                        if (time_after(jiffies, timeout)) {
+                                dev_warn(dev->dev,
+                                "timeout waiting for bus ready\n");
+                                to_cnt++;
+                                return -ETIMEDOUT;
+                        } else {
+                                to_cnt = 0;
+                                i2c_recover_bus(dev);
+                                i2c_davinci_init(dev);
+                        }
                 }
                 if (allow_sleep)
                         schedule_timeout(1);
@@ -327,6 +375,7 @@ i2c_davinci_xfer_msg(struct i2c_adapter *adap, struct i2c_msg *msg, int stop)
                                                       dev->adapter.timeout);
         if (r == 0) {
                 dev_err(dev->dev, "controller timed out\n");
+                i2c_recover_bus(dev);
                 i2c_davinci_init(dev);
                 dev->buf_len = 0;
                 return -ETIMEDOUT;