[PATCH 5.4 37/54] i2c: imx: Fix reset of I2SR_IAL flag

Greg Kroah-Hartman
2020-12-10T15:31:39Z

From: Christian Eggers <ceggers@arri.de>

commit 384a9565f70a876c2e78e58c5ca0bbf0547e4f6d upstream.

According to the "VFxxx Controller Reference Manual" (and the comment
block starting at line 97), Vybrid requires writing a one for clearing
an interrupt flag. Syncing the method for clearing I2SR_IIF in
i2c_imx_isr().

Signed-off-by: Christian Eggers <ceggers@arri.de>
Fixes: 4b775022f6fd ("i2c: imx: add struct to hold more configurable quirks")
Reviewed-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Cc: stable@vger.kernel.org
Signed-off-by: Wolfram Sang <wsa@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/i2c/busses/i2c-imx.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)

--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -414,6 +414,19 @@ static void i2c_imx_dma_free(struct imx_
dma->chan_using = NULL;
}

+static void i2c_imx_clear_irq(struct imx_i2c_struct *i2c_imx, unsigned int bits)
+{
+ unsigned int temp;
+
+ /*
+ * i2sr_clr_opcode is the value to clear all interrupts. Here we want to
+ * clear only <bits>, so we write ~i2sr_clr_opcode with just <bits>
+ * toggled. This is required because i.MX needs W0C and Vybrid uses W1C.
+ */
+ temp = ~i2c_imx->hwdata->i2sr_clr_opcode ^ bits;
+ imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR);
+}
+
static int i2c_imx_bus_busy(struct imx_i2c_struct *i2c_imx, int for_busy)
{
unsigned long orig_jiffies = jiffies;
@@ -426,8 +439,7 @@ static int i2c_imx_bus_busy(struct imx_i

/* check for arbitration lost */
if (temp & I2SR_IAL) {
- temp &= ~I2SR_IAL;
- imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR);
+ i2c_imx_clear_irq(i2c_imx, I2SR_IAL);
return -EAGAIN;
}

@@ -599,9 +611,7 @@ static irqreturn_t i2c_imx_isr(int irq,
if (temp & I2SR_IIF) {
/* save status register */
i2c_imx->i2csr = temp;
- temp &= ~I2SR_IIF;
- temp |= (i2c_imx->hwdata->i2sr_clr_opcode & I2SR_IIF);
- imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2SR);
+ i2c_imx_clear_irq(i2c_imx, I2SR_IIF);
wake_up(&i2c_imx->queue);
return IRQ_HANDLED;
}