i2c: xlp9xx: Check for Bus state before every transfer

[mirror_ubuntu-bionic-kernel.git] / drivers / i2c / busses / i2c-xlp9xx.c

diff --git a/drivers/i2c/busses/i2c-xlp9xx.c b/drivers/i2c/busses/i2c-xlp9xx.c
index b970bf8f38e57f0ac3b072620bb96de15796b744..42dd1fa0b6442550577fbeca13c4c0ea220896ba 100644 (file)
--- a/drivers/i2c/busses/i2c-xlp9xx.c
+++ b/drivers/i2c/busses/i2c-xlp9xx.c
@@ -16,6 +16,7 @@
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
+#include <linux/delay.h>
 
 #define XLP9XX_I2C_DIV                 0x0
 #define XLP9XX_I2C_CTRL                        0x1
@@ -36,6 +37,8 @@
 #define XLP9XX_I2C_TIMEOUT             0X10
 #define XLP9XX_I2C_GENCALLADDR         0x11
 
+#define XLP9XX_I2C_STATUS_BUSY         BIT(0)
+
 #define XLP9XX_I2C_CMD_START           BIT(7)
 #define XLP9XX_I2C_CMD_STOP            BIT(6)
 #define XLP9XX_I2C_CMD_READ            BIT(5)
@@ -71,6 +74,7 @@
 #define XLP9XX_I2C_HIGH_FREQ           400000
 #define XLP9XX_I2C_FIFO_SIZE           0x80U
 #define XLP9XX_I2C_TIMEOUT_MS          1000
+#define XLP9XX_I2C_BUSY_TIMEOUT                50
 
 #define XLP9XX_I2C_FIFO_WCNT_MASK      0xff
 #define XLP9XX_I2C_STATUS_ERRMASK      (XLP9XX_I2C_INTEN_ARLOST | \
@@ -125,7 +129,16 @@ static void xlp9xx_i2c_update_rx_fifo_thres(struct xlp9xx_i2c_dev *priv)
 {
        u32 thres;
 
-       thres = min(priv->msg_buf_remaining, XLP9XX_I2C_FIFO_SIZE);
+       if (priv->len_recv)
+               /* interrupt after the first read to examine
+                * the length byte before proceeding further
+                */
+               thres = 1;
+       else if (priv->msg_buf_remaining > XLP9XX_I2C_FIFO_SIZE)
+               thres = XLP9XX_I2C_FIFO_SIZE;
+       else
+               thres = priv->msg_buf_remaining;
+
        xlp9xx_write_i2c_reg(priv, XLP9XX_I2C_MFIFOCTRL,
                             thres << XLP9XX_I2C_MFIFOCTRL_HITH_SHIFT);
 }
@@ -144,7 +157,7 @@ static void xlp9xx_i2c_fill_tx_fifo(struct xlp9xx_i2c_dev *priv)
 
 static void xlp9xx_i2c_drain_rx_fifo(struct xlp9xx_i2c_dev *priv)
 {
-       u32 len, i;
+       u32 len, i, val;
        u8 rlen, *buf = priv->msg_buf;
 
        len = xlp9xx_read_i2c_reg(priv, XLP9XX_I2C_FIFOWCNT) &
@@ -156,19 +169,27 @@ static void xlp9xx_i2c_drain_rx_fifo(struct xlp9xx_i2c_dev *priv)
                rlen = xlp9xx_read_i2c_reg(priv, XLP9XX_I2C_MRXFIFO);
                *buf++ = rlen;
                len--;
+
                if (priv->client_pec)
                        ++rlen;
                /* update remaining bytes and message length */
                priv->msg_buf_remaining = rlen;
                priv->msg_len = rlen + 1;
                priv->len_recv = false;
-       }
 
-       len = min(priv->msg_buf_remaining, len);
-       for (i = 0; i < len; i++, buf++)
-               *buf = xlp9xx_read_i2c_reg(priv, XLP9XX_I2C_MRXFIFO);
+               /* Update transfer length to read only actual data */
+               val = xlp9xx_read_i2c_reg(priv, XLP9XX_I2C_CTRL);
+               val = (val & ~XLP9XX_I2C_CTRL_MCTLEN_MASK) |
+                       ((rlen + 1) << XLP9XX_I2C_CTRL_MCTLEN_SHIFT);
+               xlp9xx_write_i2c_reg(priv, XLP9XX_I2C_CTRL, val);
+       } else {
+               len = min(priv->msg_buf_remaining, len);
+               for (i = 0; i < len; i++, buf++)
+                       *buf = xlp9xx_read_i2c_reg(priv, XLP9XX_I2C_MRXFIFO);
+
+               priv->msg_buf_remaining -= len;
+       }
 
-       priv->msg_buf_remaining -= len;
        priv->msg_buf = buf;
 
        if (priv->msg_buf_remaining)
@@ -224,6 +245,26 @@ xfer_done:
        return IRQ_HANDLED;
 }
 
+static int xlp9xx_i2c_check_bus_status(struct xlp9xx_i2c_dev *priv)
+{
+       u32 status;
+       u32 busy_timeout = XLP9XX_I2C_BUSY_TIMEOUT;
+
+       while (busy_timeout) {
+               status = xlp9xx_read_i2c_reg(priv, XLP9XX_I2C_STATUS);
+               if ((status & XLP9XX_I2C_STATUS_BUSY) == 0)
+                       break;
+
+               busy_timeout--;
+               usleep_range(1000, 1100);
+       }
+
+       if (!busy_timeout)
+               return -EIO;
+
+       return 0;
+}
+
 static int xlp9xx_i2c_init(struct xlp9xx_i2c_dev *priv)
 {
        u32 prescale;
@@ -324,7 +365,8 @@ static int xlp9xx_i2c_xfer_msg(struct xlp9xx_i2c_dev *priv, struct i2c_msg *msg,
                dev_dbg(priv->dev, "transfer error %x!\n", priv->msg_err);
                if (priv->msg_err & XLP9XX_I2C_INTEN_BUSERR)
                        xlp9xx_i2c_init(priv);
-               return -EIO;
+               return (priv->msg_err & XLP9XX_I2C_INTEN_NACKADDR) ?
+                       -ENXIO : -EIO;
        }
 
        if (timeleft == 0) {
@@ -345,6 +387,14 @@ static int xlp9xx_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
        int i, ret;
        struct xlp9xx_i2c_dev *priv = i2c_get_adapdata(adap);
 
+       ret = xlp9xx_i2c_check_bus_status(priv);
+       if (ret) {
+               xlp9xx_i2c_init(priv);
+               ret = xlp9xx_i2c_check_bus_status(priv);
+               if (ret)
+                       return ret;
+       }
+
        for (i = 0; i < num; i++) {
                ret = xlp9xx_i2c_xfer_msg(priv, &msgs[i], i == num - 1);
                if (ret != 0)
@@ -356,8 +406,8 @@ static int xlp9xx_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 
 static u32 xlp9xx_i2c_functionality(struct i2c_adapter *adapter)
 {
-       return I2C_FUNC_SMBUS_EMUL | I2C_FUNC_I2C |
-               I2C_FUNC_10BIT_ADDR;
+       return I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_READ_BLOCK_DATA |
+                       I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR;
 }
 
 static const struct i2c_algorithm xlp9xx_i2c_algo = {