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Subject[PATCH 11/12] i2c: algo: bit: add flag to whitelist atomic transfers
Date
Use the new xfer_atomic callback to check a newly introduced flag to
whitelist atomic transfers. This will report configurations which
worked accidently.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
drivers/i2c/algos/i2c-algo-bit.c | 22 ++++++++++++++++++++--
include/linux/i2c-algo-bit.h | 1 +
2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/algos/i2c-algo-bit.c b/drivers/i2c/algos/i2c-algo-bit.c
index 5e5990a83da5..913db013fe90 100644
--- a/drivers/i2c/algos/i2c-algo-bit.c
+++ b/drivers/i2c/algos/i2c-algo-bit.c
@@ -603,6 +603,23 @@ static int bit_xfer(struct i2c_adapter *i2c_adap,
return ret;
}

+/*
+ * We print a warning when we are not flagged to support atomic transfers but
+ * will try anyhow. That's what the I2C core would do as well. Sadly, we can't
+ * modify the algorithm struct at probe time because this struct is exported
+ * 'const'.
+ */
+static int bit_xfer_atomic(struct i2c_adapter *i2c_adap, struct i2c_msg msgs[],
+ int num)
+{
+ struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
+
+ if (!adap->can_do_atomic)
+ dev_warn(&i2c_adap->dev, "not flagged for atomic transfers\n");
+
+ return bit_xfer(i2c_adap, msgs, num);
+}
+
static u32 bit_func(struct i2c_adapter *adap)
{
return I2C_FUNC_I2C | I2C_FUNC_NOSTART | I2C_FUNC_SMBUS_EMUL |
@@ -615,8 +632,9 @@ static u32 bit_func(struct i2c_adapter *adap)
/* -----exported algorithm data: ------------------------------------- */

const struct i2c_algorithm i2c_bit_algo = {
- .master_xfer = bit_xfer,
- .functionality = bit_func,
+ .master_xfer = bit_xfer,
+ .master_xfer_atomic = bit_xfer_atomic,
+ .functionality = bit_func,
};
EXPORT_SYMBOL(i2c_bit_algo);

diff --git a/include/linux/i2c-algo-bit.h b/include/linux/i2c-algo-bit.h
index 69045df78e2d..7fd5575a368f 100644
--- a/include/linux/i2c-algo-bit.h
+++ b/include/linux/i2c-algo-bit.h
@@ -33,6 +33,7 @@ struct i2c_algo_bit_data {
minimum 5 us for standard-mode I2C and SMBus,
maximum 50 us for SMBus */
int timeout; /* in jiffies */
+ bool can_do_atomic; /* callbacks don't sleep, we can be atomic */
};

int i2c_bit_add_bus(struct i2c_adapter *);
--
2.11.0
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