linux-kernel - [PATCH v6] i2c: imx: make bus recovery through pinctrl optional

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Date:   Wed, 7 Sep 2016 12:03:16 -0500
From:   Li Yang <leoyang.li@....com>
To:     Wolfram Sang <wsa@...-dreams.de>, <linux-i2c@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <linux-gpio@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
CC:     Li Yang <leoyang.li@....com>, Gao Pan <pandy.gao@....com>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
Subject: [PATCH v6] i2c: imx: make bus recovery through pinctrl optional

Since commit 1c4b6c3bcf30 ("i2c: imx: implement bus recovery") the
driver starts to use gpio/pinctrl to do i2c bus recovery.  But pinctrl
is not always available for platforms with this controller such as
ls1021a and ls1043a, and the device tree binding also mentioned this
gpio based recovery mechanism as optional.  The patch makes it really
optional that the probe function won't bailout but just disable the
bus recovery function when pinctrl is not usable.

Signed-off-by: Li Yang <leoyang.li@....com>
Cc: Gao Pan <pandy.gao@....com>
Cc: Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Acked-by: Linus Walleij <linus.walleij@...aro.org>
---
v6:
Update code comment

v5:
Revert the last minute change of recovery info initialization timing, it
will cause problem if initialized after i2c_add_numbered_adapter()

v4:
Remove the use of IS_ERR_OR_NULL
Move the condition judgement to i2c_imx_init_recovery_info()
Change the timing of recovery initialization to be after bus registration

v3:
Rebased to Wolfram's for-next branch
Added acked-by from Linus Walleij
Update to use new nxp email addresses due to company merge

 drivers/i2c/busses/i2c-imx.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 1844bc9..f52ff47 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -989,6 +989,14 @@ static void i2c_imx_init_recovery_info(struct imx_i2c_struct *i2c_imx,
 {
 	struct i2c_bus_recovery_info *rinfo = &i2c_imx->rinfo;
 
+	/* If pinctrl is not available disable bus recovery */
+	if (IS_ERR(i2c_imx->pinctrl))
+		i2c_imx->pinctrl = NULL;
+	if (!i2c_imx->pinctrl) {
+		dev_info(&pdev->dev, "can't get pinctrl, bus recovery not supported\n");
+		return;
+	}
+
 	i2c_imx->pinctrl_pins_default = pinctrl_lookup_state(i2c_imx->pinctrl,
 			PINCTRL_STATE_DEFAULT);
 	i2c_imx->pinctrl_pins_gpio = pinctrl_lookup_state(i2c_imx->pinctrl,
@@ -1081,8 +1089,19 @@ static int i2c_imx_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	/*
+	 * If pinctrl is available it might be possible to switch the
+	 * SDA and SCL lines to their GPIO functions and do a recovery
+	 * procedure in this mode. If there is anything wrong with
+	 * pinctrl we cannot do this and simply not enable it.
+	 */
 	i2c_imx->pinctrl = devm_pinctrl_get(&pdev->dev);
-	if (IS_ERR(i2c_imx->pinctrl)) {
+	/*
+	 * Bailout on critical errors, continue for other errors.
+	 * Bus recovery will not be enabled if pinctrl is not available.
+	 */
+	if (PTR_ERR(i2c_imx->pinctrl) == -ENOMEM ||
+			PTR_ERR(i2c_imx->pinctrl) == -EPROBE_DEFER) {
 		ret = PTR_ERR(i2c_imx->pinctrl);
 		goto clk_disable;
 	}
@@ -1125,6 +1144,7 @@ static int i2c_imx_probe(struct platform_device *pdev)
 			i2c_imx, IMX_I2C_I2CR);
 	imx_i2c_write_reg(i2c_imx->hwdata->i2sr_clr_opcode, i2c_imx, IMX_I2C_I2SR);
 
+	/* Init bus recovery info if supported */
 	i2c_imx_init_recovery_info(i2c_imx, pdev);
 
 	/* Add I2C adapter */
-- 
1.9.0