From d9cfe2ce246845b9cca0ec1b881e826965893c58 Mon Sep 17 00:00:00 2001 From: Wolfram Sang 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 Reviewed-by: Niklas Söderlund Reviewed-by: Andy Shevchenko Tested-by: Jarkko Nikula Acked-by: Jarkko Nikula Signed-off-by: Wolfram Sang --- 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