CHROMIUM: Input: atmel_mxt_ts - dump mxt_read/write_reg

For verbose on-the-wire debugging.
Prints DUMP_LEN bytes (in hex) per line.

Signed-off-by: Daniel Kurtz <djkurtz@chromium.org>
BUG=chromium-os:27713
TEST=builds clean w/ & w/out DEBUG defined.
  If DEBUG defined, bytes read & written over i2c by atmel_mxt_ts should
  appear in /var/log/messages

Change-Id: Ib1b8301a25bb915fea47e4dd62ff261ae5284c3c
Reviewed-on: https://gerrit.chromium.org/gerrit/17943
Commit-Ready: Daniel Kurtz <djkurtz@chromium.org>
Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>
Tested-by: Daniel Kurtz <djkurtz@chromium.org>

diff --git a/drivers/input/touchscreen/atmel_mxt_ts.c b/drivers/input/touchscreen/atmel_mxt_ts.c
index 0c960cc..5e72929 100644 (file)
--- a/drivers/input/touchscreen/atmel_mxt_ts.c
+++ b/drivers/input/touchscreen/atmel_mxt_ts.c
@@ -397,6 +397,33 @@ static int mxt_fw_write(struct i2c_client *client,
        return 0;
 }
 
+#ifdef DEBUG
+#define DUMP_LEN       16
+static void mxt_dump_xfer(struct device *dev, const char *func, u16 reg,
+                         u16 len, const u8 *val)
+{
+       /* Rough guess for string size */
+       char str[DUMP_LEN * 3 + 2];
+       int i;
+       size_t n;
+
+       for (i = 0, n = 0; i < len; i++) {
+               n += snprintf(&str[n], sizeof(str) - n, "%02x ", val[i]);
+               if ((i + 1) % DUMP_LEN == 0 || (i + 1) == len) {
+                       dev_dbg(dev,
+                               "%s(reg: %d len: %d offset: 0x%02x): %s\n",
+                               func, reg, len, (i / DUMP_LEN) * DUMP_LEN,
+                               str);
+                       n = 0;
+               }
+       }
+}
+#undef DUMP_LEN
+#else
+static void mxt_dump_xfer(struct device *dev, const char *func, u16 reg,
+                         u16 len, const u8 *val) { }
+#endif
+
 static int mxt_read_reg(struct i2c_client *client, u16 reg, u16 len, void *val)
 {
        struct i2c_msg xfer[2];
@@ -422,6 +449,8 @@ static int mxt_read_reg(struct i2c_client *client, u16 reg, u16 len, void *val)
                return -EIO;
        }
 
+       mxt_dump_xfer(&client->dev, __func__, reg, len, val);
+
        return 0;
 }
 
@@ -435,6 +464,8 @@ static int mxt_write_reg(struct i2c_client *client, u16 reg, u16 len,
        buf[1] = (reg >> 8) & 0xff;
        memcpy(&buf[2], val, len);
 
+       mxt_dump_xfer(&client->dev, __func__, reg, len, val);
+
        if (i2c_master_send(client, buf, count) != count) {
                dev_err(&client->dev, "%s: i2c write failed\n", __func__);
                return -EIO;