linux-kernel - [PATCHv3 1/2] i2c: designware: introduce a custom scl recovery for SoCFPGA platforms

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Date:   Mon, 13 Jun 2022 16:00:31 -0500
From:   Dinh Nguyen <dinguyen@...nel.org>
To:     jarkko.nikula@...ux.intel.com
Cc:     dinguyen@...nel.org, andriy.shevchenko@...ux.intel.com,
        mika.westerberg@...ux.intel.com, robh+dt@...nel.org,
        krzk+dt@...nel.org, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: [PATCHv3 1/2] i2c: designware: introduce a custom scl recovery for SoCFPGA platforms

The I2C pins on the SoCFPGA platforms do not go through a GPIO module,
thus cannot be recovered by the default method of by doing a GPIO access.
Only a reset of the I2C IP block can a recovery be successful.

The assignment of the recover_bus needs to get done before the call to
devm_gpiod_get_optional(), otherwise, the assignment is not taking place
because of an error after returning from devm_gpiod_get_optional().

Signed-off-by: Dinh Nguyen <dinguyen@...nel.org>
---
v3: simplify the function
    update commit message
v2: remove change to MODEL_MASK
    s/i2c_custom_scl_recovery/i2c_socfpga_scl_recovery
---
 drivers/i2c/busses/i2c-designware-core.h    |  1 +
 drivers/i2c/busses/i2c-designware-master.c  | 12 ++++++++++++
 drivers/i2c/busses/i2c-designware-platdrv.c |  1 +
 3 files changed, 14 insertions(+)

diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 70b80e710990..7b22ec1d6a96 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -303,6 +303,7 @@ struct dw_i2c_dev {
 #define MODEL_MSCC_OCELOT	BIT(8)
 #define MODEL_BAIKAL_BT1	BIT(9)
 #define MODEL_AMD_NAVI_GPU	BIT(10)
+#define MODEL_SOCFPGA		BIT(11)
 #define MODEL_MASK		GENMASK(11, 8)
 
 /*
diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
index 44a94b225ed8..502820b812a5 100644
--- a/drivers/i2c/busses/i2c-designware-master.c
+++ b/drivers/i2c/busses/i2c-designware-master.c
@@ -813,12 +813,24 @@ static void i2c_dw_unprepare_recovery(struct i2c_adapter *adap)
 	i2c_dw_init_master(dev);
 }
 
+static int i2c_socfpga_scl_recovery(struct i2c_adapter *adap)
+{
+	i2c_dw_prepare_recovery(adap);
+	i2c_dw_unprepare_recovery(adap);
+	return 0;
+}
+
 static int i2c_dw_init_recovery_info(struct dw_i2c_dev *dev)
 {
 	struct i2c_bus_recovery_info *rinfo = &dev->rinfo;
 	struct i2c_adapter *adap = &dev->adapter;
 	struct gpio_desc *gpio;
 
+	if ((dev->flags & MODEL_MASK) == MODEL_SOCFPGA) {
+		rinfo->recover_bus = i2c_socfpga_scl_recovery;
+		adap->bus_recovery_info = rinfo;
+	}
+
 	gpio = devm_gpiod_get_optional(dev->dev, "scl", GPIOD_OUT_HIGH);
 	if (IS_ERR_OR_NULL(gpio))
 		return PTR_ERR_OR_ZERO(gpio);
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 70ade5306e45..b33e015e6732 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -153,6 +153,7 @@ static const struct of_device_id dw_i2c_of_match[] = {
 	{ .compatible = "snps,designware-i2c", },
 	{ .compatible = "mscc,ocelot-i2c", .data = (void *)MODEL_MSCC_OCELOT },
 	{ .compatible = "baikal,bt1-sys-i2c", .data = (void *)MODEL_BAIKAL_BT1 },
+	{ .compatible = "intel,socfpga-i2c", .data = (void *)MODEL_SOCFPGA },
 	{},
 };
 MODULE_DEVICE_TABLE(of, dw_i2c_of_match);
-- 
2.25.1