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From 5faad0781d619f13723886e36dfed3ea7eeff00f Mon Sep 17 00:00:00 2001
From: Dave Stevenson <dave.stevenson@raspberrypi.com>
Date: Tue, 23 May 2023 14:31:03 +0100
Subject: [PATCH] i2c-bcm2835: Implement I2C_M_IGNORE_NAK
Now that transfers aren't aborted immediately (and uncleanly) on
errors, and the FIFOs are always drained after all transfers, we
can implement I2C_M_IGNORE_NAK by ignoring the returned error
value.
Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
---
drivers/i2c/busses/i2c-bcm2835.c | 11 +++++++++--
1 file changed, 9 insertions(+), 2 deletions(-)
--- a/drivers/i2c/busses/i2c-bcm2835.c
+++ b/drivers/i2c/busses/i2c-bcm2835.c
@@ -443,6 +443,7 @@ static int bcm2835_i2c_xfer(struct i2c_a
{
struct bcm2835_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
unsigned long time_left;
+ bool ignore_nak = false;
int i;
if (debug)
@@ -452,12 +453,15 @@ static int bcm2835_i2c_xfer(struct i2c_a
for (i = 0; i < num; i++)
bcm2835_debug_print_msg(i2c_dev, &msgs[i], i + 1, num, __func__);
- for (i = 0; i < (num - 1); i++)
+ for (i = 0; i < (num - 1); i++) {
if (msgs[i].flags & I2C_M_RD) {
dev_warn_once(i2c_dev->dev,
"only one read message supported, has to be last\n");
return -EOPNOTSUPP;
}
+ if (msgs[i].flags & I2C_M_IGNORE_NAK)
+ ignore_nak = true;
+ }
i2c_dev->curr_msg = msgs;
i2c_dev->num_msgs = num;
@@ -471,6 +475,9 @@ static int bcm2835_i2c_xfer(struct i2c_a
bcm2835_i2c_finish_transfer(i2c_dev);
+ if (ignore_nak)
+ i2c_dev->msg_err &= ~BCM2835_I2C_S_ERR;
+
if (debug > 1 || (debug && (!time_left || i2c_dev->msg_err)))
bcm2835_debug_print(i2c_dev);
i2c_dev->debug_num_msgs = 0;
@@ -497,7 +504,7 @@ static int bcm2835_i2c_xfer(struct i2c_a
static u32 bcm2835_i2c_func(struct i2c_adapter *adap)
{
- return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
}
static const struct i2c_algorithm bcm2835_i2c_algo = {
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