[RFC V2 02/12] i2c: add quirk checks to core

[Wolfram Sang]

From: Wolfram Sang <wsa+renesas at sang-engineering.com>

Let the core do the checks if HW quirks prevent a transfer. Saves code
from drivers and adds consistency.

Signed-off-by: Wolfram Sang <wsa+renesas at sang-engineering.com>
---
 drivers/i2c/i2c-core.c | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 62 insertions(+)

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 210cf4874cb7ea..c5ca0e4006edb7 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -1929,6 +1929,65 @@ module_exit(i2c_exit);
  * ----------------------------------------------------
  */
 
+/* Check if val is exceeding the quirk IFF quirk is non 0 */
+#define i2c_quirk_exceeded(val, quirk) ((quirk) && ((val) > (quirk)))
+
+static int i2c_quirk_error(struct i2c_adapter *adap, struct i2c_msg *msg, char *err_msg)
+{
+	dev_err_ratelimited(&adap->dev, "quirk: %s (addr 0x%04x, size %u, %s)\n",
+			    err_msg, msg->addr, msg->len,
+			    msg->flags & I2C_M_RD ? "read" : "write");
+	return -EOPNOTSUPP;
+}
+
+static int i2c_check_for_quirks(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
+{
+	const struct i2c_adapter_quirks *q = adap->quirks;
+	int max_num = q->max_num_msgs, i;
+	bool do_len_check = true;
+
+	if (q->flags & I2C_AQ_COMB) {
+		max_num = 2;
+
+		/* special checks for combined messages */
+		if (num == 2) {
+			if (q->flags & I2C_AQ_COMB_WRITE_FIRST && msgs[0].flags & I2C_M_RD)
+				return i2c_quirk_error(adap, &msgs[0], "1st comb msg not write");
+
+			if (q->flags & I2C_AQ_COMB_READ_SECOND && !(msgs[1].flags & I2C_M_RD))
+				return i2c_quirk_error(adap, &msgs[1], "2nd comb msg not read");
+
+			if (q->flags & I2C_AQ_COMB_SAME_ADDR && msgs[0].addr != msgs[1].addr)
+				return i2c_quirk_error(adap, &msgs[0], "addresses do not match");
+
+			if (i2c_quirk_exceeded(msgs[0].len, q->max_comb_1st_msg_len))
+				return i2c_quirk_error(adap, &msgs[0], "msg too long");
+
+			if (i2c_quirk_exceeded(msgs[1].len, q->max_comb_2nd_msg_len))
+				return i2c_quirk_error(adap, &msgs[1], "msg too long");
+
+			do_len_check = false;
+		}
+	}
+
+	if (i2c_quirk_exceeded(num, max_num))
+		return i2c_quirk_error(adap, &msgs[0], "too many messages");
+
+	for (i = 0; i < num; i++) {
+		u16 len = msgs[i].len;
+
+		if (msgs[i].flags & I2C_M_RD) {
+			if (do_len_check && i2c_quirk_exceeded(len, q->max_read_len))
+				return i2c_quirk_error(adap, &msgs[i], "msg too long");
+		} else {
+			if (do_len_check && i2c_quirk_exceeded(len, q->max_write_len))
+				return i2c_quirk_error(adap, &msgs[i], "msg too long");
+		}
+	}
+
+	return 0;
+}
+
 /**
  * __i2c_transfer - unlocked flavor of i2c_transfer
  * @adap: Handle to I2C bus
@@ -1946,6 +2005,9 @@ int __i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
 	unsigned long orig_jiffies;
 	int ret, try;
 
+	if (adap->quirks && i2c_check_for_quirks(adap, msgs, num))
+		return -EOPNOTSUPP;
+
 	/* i2c_trace_msg gets enabled when tracepoint i2c_transfer gets
 	 * enabled.  This is an efficient way of keeping the for-loop from
 	 * being executed when not needed.
-- 
2.1.4