i2c: i2c_cdns: Add support for handling arbitration lost
authorSiva Durga Prasad Paladugu <siva.durga.paladugu@xilinx.com>
Thu, 7 Mar 2019 10:52:49 +0000 (11:52 +0100)
committerHeiko Schocher <hs@denx.de>
Fri, 8 Mar 2019 04:52:38 +0000 (05:52 +0100)
This patch adds support for handling arbitration lost
in case of multi master mode. When an arbitration lost
is detected, it retries for 10 times before failing.

Signed-off-by: Siva Durga Prasad Paladugu <siva.durga.paladugu@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
drivers/i2c/i2c-cdns.c

index b391c0ba49b852f337cc8d58f1192ea95ca1420e..1af94d17614554cda01321f1a6626e3db234ab44 100644 (file)
@@ -80,6 +80,8 @@ struct cdns_i2c_regs {
 
 #define CDNS_I2C_BROKEN_HOLD_BIT       BIT(0)
 
+#define CDNS_I2C_ARB_LOST_MAX_RETRIES  10
+
 #ifdef DEBUG
 static void cdns_i2c_debug_status(struct cdns_i2c_regs *cdns_i2c)
 {
@@ -234,11 +236,17 @@ static int cdns_i2c_set_bus_speed(struct udevice *dev, unsigned int speed)
        return 0;
 }
 
+static inline u32 is_arbitration_lost(struct cdns_i2c_regs *regs)
+{
+       return (readl(&regs->interrupt_status) & CDNS_I2C_INTERRUPT_ARBLOST);
+}
+
 static int cdns_i2c_write_data(struct i2c_cdns_bus *i2c_bus, u32 addr, u8 *data,
                               u32 len)
 {
        u8 *cur_data = data;
        struct cdns_i2c_regs *regs = i2c_bus->regs;
+       u32 ret;
 
        /* Set the controller in Master transmit mode and clear FIFO */
        setbits_le32(&regs->control, CDNS_I2C_CONTROL_CLR_FIFO);
@@ -255,25 +263,38 @@ static int cdns_i2c_write_data(struct i2c_cdns_bus *i2c_bus, u32 addr, u8 *data,
 
        writel(addr, &regs->address);
 
-       while (len--) {
+       while (len-- && !is_arbitration_lost(regs)) {
                writel(*(cur_data++), &regs->data);
                if (readl(&regs->transfer_size) == CDNS_I2C_FIFO_DEPTH) {
-                       if (!cdns_i2c_wait(regs, CDNS_I2C_INTERRUPT_COMP)) {
-                               /* Release the bus */
-                               clrbits_le32(&regs->control,
-                                            CDNS_I2C_CONTROL_HOLD);
-                               return -ETIMEDOUT;
-                       }
+                       ret = cdns_i2c_wait(regs, CDNS_I2C_INTERRUPT_COMP |
+                                           CDNS_I2C_INTERRUPT_ARBLOST);
+                       if (ret & CDNS_I2C_INTERRUPT_ARBLOST)
+                               return -EAGAIN;
+                       if (ret & CDNS_I2C_INTERRUPT_COMP)
+                               continue;
+                       /* Release the bus */
+                       clrbits_le32(&regs->control,
+                                    CDNS_I2C_CONTROL_HOLD);
+                       return -ETIMEDOUT;
                }
        }
 
+       if (len && is_arbitration_lost(regs))
+               return -EAGAIN;
+
        /* All done... release the bus */
        if (!i2c_bus->hold_flag)
                clrbits_le32(&regs->control, CDNS_I2C_CONTROL_HOLD);
 
        /* Wait for the address and data to be sent */
-       if (!cdns_i2c_wait(regs, CDNS_I2C_INTERRUPT_COMP))
+       ret = cdns_i2c_wait(regs, CDNS_I2C_INTERRUPT_COMP |
+                           CDNS_I2C_INTERRUPT_ARBLOST);
+       if (!(ret & (CDNS_I2C_INTERRUPT_ARBLOST |
+                    CDNS_I2C_INTERRUPT_COMP)))
                return -ETIMEDOUT;
+       if (ret & CDNS_I2C_INTERRUPT_ARBLOST)
+               return -EAGAIN;
+
        return 0;
 }
 
@@ -289,6 +310,7 @@ static int cdns_i2c_read_data(struct i2c_cdns_bus *i2c_bus, u32 addr, u8 *data,
        struct cdns_i2c_regs *regs = i2c_bus->regs;
        int curr_recv_count;
        int updatetx, hold_quirk;
+       u32 ret;
 
        /* Check the hardware can handle the requested bytes */
        if ((recv_count < 0))
@@ -317,7 +339,7 @@ static int cdns_i2c_read_data(struct i2c_cdns_bus *i2c_bus, u32 addr, u8 *data,
 
        hold_quirk = (i2c_bus->quirks & CDNS_I2C_BROKEN_HOLD_BIT) && updatetx;
 
-       while (recv_count) {
+       while (recv_count && !is_arbitration_lost(regs)) {
                while (readl(&regs->status) & CDNS_I2C_STATUS_RXDV) {
                        if (recv_count < CDNS_I2C_FIFO_DEPTH &&
                            !i2c_bus->hold_flag) {
@@ -366,8 +388,13 @@ static int cdns_i2c_read_data(struct i2c_cdns_bus *i2c_bus, u32 addr, u8 *data,
        }
 
        /* Wait for the address and data to be sent */
-       if (!cdns_i2c_wait(regs, CDNS_I2C_INTERRUPT_COMP))
+       ret = cdns_i2c_wait(regs, CDNS_I2C_INTERRUPT_COMP |
+                           CDNS_I2C_INTERRUPT_ARBLOST);
+       if (!(ret & (CDNS_I2C_INTERRUPT_ARBLOST |
+                    CDNS_I2C_INTERRUPT_COMP)))
                return -ETIMEDOUT;
+       if (ret & CDNS_I2C_INTERRUPT_ARBLOST)
+               return -EAGAIN;
 
        return 0;
 }
@@ -376,8 +403,11 @@ static int cdns_i2c_xfer(struct udevice *dev, struct i2c_msg *msg,
                         int nmsgs)
 {
        struct i2c_cdns_bus *i2c_bus = dev_get_priv(dev);
-       int ret, count;
+       int ret = 0;
+       int count;
        bool hold_quirk;
+       struct i2c_msg *message = msg;
+       int num_msgs = nmsgs;
 
        hold_quirk = !!(i2c_bus->quirks & CDNS_I2C_BROKEN_HOLD_BIT);
 
@@ -403,7 +433,8 @@ static int cdns_i2c_xfer(struct udevice *dev, struct i2c_msg *msg,
        }
 
        debug("i2c_xfer: %d messages\n", nmsgs);
-       for (; nmsgs > 0; nmsgs--, msg++) {
+       for (u8 retry = 0; retry < CDNS_I2C_ARB_LOST_MAX_RETRIES &&
+            nmsgs > 0; nmsgs--, msg++) {
                debug("i2c_xfer: chip=0x%x, len=0x%x\n", msg->addr, msg->len);
                if (msg->flags & I2C_M_RD) {
                        ret = cdns_i2c_read_data(i2c_bus, msg->addr, msg->buf,
@@ -412,13 +443,22 @@ static int cdns_i2c_xfer(struct udevice *dev, struct i2c_msg *msg,
                        ret = cdns_i2c_write_data(i2c_bus, msg->addr, msg->buf,
                                                  msg->len);
                }
+               if (ret == -EAGAIN) {
+                       msg = message;
+                       nmsgs = num_msgs;
+                       retry++;
+                       printf("%s,arbitration lost, retrying:%d\n", __func__,
+                              retry);
+                       continue;
+               }
+
                if (ret) {
                        debug("i2c_write: error sending\n");
                        return -EREMOTEIO;
                }
        }
 
-       return 0;
+       return ret;
 }
 
 static int cdns_i2c_ofdata_to_platdata(struct udevice *dev)