From d9cfe2ce246845b9cca0ec1b881e826965893c58 Mon Sep 17 00:00:00 2001
From: Wolfram Sang <wsa+renesas@sang-engineering.com>
Date: Mon, 23 Jul 2018 22:26:05 +0200
Subject: [PATCH] i2c: quirks: add zero length checks
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit
Some adapters do not support a message length of 0. Add this as a quirk
so drivers don't have to open code it.
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Tested-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Acked-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
---
drivers/i2c/i2c-core-base.c | 6 ++++++
include/linux/i2c.h | 4 ++++
2 files changed, 10 insertions(+)
diff --git a/drivers/i2c/i2c-core-base.c b/drivers/i2c/i2c-core-base.c
index 02d6f27b19e4..a26b3e9cc441 100644
--- a/drivers/i2c/i2c-core-base.c
+++ b/drivers/i2c/i2c-core-base.c
@@ -1839,9 +1839,15 @@ static int i2c_check_for_quirks(struct i2c_adapter *adap, struct i2c_msg *msgs,
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");
+
+ if (q->flags & I2C_AQ_NO_ZERO_LEN_READ && len == 0)
+ return i2c_quirk_error(adap, &msgs[i], "no zero length");
} else {
if (do_len_check && i2c_quirk_exceeded(len, q->max_write_len))
return i2c_quirk_error(adap, &msgs[i], "msg too long");
+
+ if (q->flags & I2C_AQ_NO_ZERO_LEN_WRITE && len == 0)
+ return i2c_quirk_error(adap, &msgs[i], "no zero length");
}
}
diff --git a/include/linux/i2c.h b/include/linux/i2c.h
index bc8d42f8544f..2a98d0886d2e 100644
--- a/include/linux/i2c.h
+++ b/include/linux/i2c.h
@@ -661,6 +661,10 @@ struct i2c_adapter_quirks {
I2C_AQ_COMB_READ_SECOND | I2C_AQ_COMB_SAME_ADDR)
/* clock stretching is not supported */
#define I2C_AQ_NO_CLK_STRETCH BIT(4)
+/* message cannot have length of 0 */
+#define I2C_AQ_NO_ZERO_LEN_READ BIT(5)
+#define I2C_AQ_NO_ZERO_LEN_WRITE BIT(6)
+#define I2C_AQ_NO_ZERO_LEN (I2C_AQ_NO_ZERO_LEN_READ | I2C_AQ_NO_ZERO_LEN_WRITE)
/*
* i2c_adapter is the structure used to identify a physical i2c bus along
--
2.30.9