[PATCH 5.4 064/110] can: tcan4x5x: tcan4x5x_parse_config(): reset device before register access

Greg Kroah-Hartman
2020-01-30T18:44:30Z

From: Sean Nyekjaer <sean@geanix.com>

[ Upstream commit c3083124e6a1c0d6cd4fe3b3f627b488bd3b10c4 ]

It's a good idea to reset a ip-block/spi device before using it, this
patch will reset the device.

And a generic reset function if needed elsewhere.

Signed-off-by: Sean Nyekjaer <sean@geanix.com>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/net/can/m_can/tcan4x5x.c | 27 ++++++++++++++++++++++++++-
1 file changed, 26 insertions(+), 1 deletion(-)

diff --git a/drivers/net/can/m_can/tcan4x5x.c b/drivers/net/can/m_can/tcan4x5x.c
index d797912e665a5..b233756345f83 100644
--- a/drivers/net/can/m_can/tcan4x5x.c
+++ b/drivers/net/can/m_can/tcan4x5x.c
@@ -164,6 +164,28 @@ static void tcan4x5x_check_wake(struct tcan4x5x_priv *priv)
}
}

+static int tcan4x5x_reset(struct tcan4x5x_priv *priv)
+{
+ int ret = 0;
+
+ if (priv->reset_gpio) {
+ gpiod_set_value(priv->reset_gpio, 1);
+
+ /* tpulse_width minimum 30us */
+ usleep_range(30, 100);
+ gpiod_set_value(priv->reset_gpio, 0);
+ } else {
+ ret = regmap_write(priv->regmap, TCAN4X5X_CONFIG,
+ TCAN4X5X_SW_RESET);
+ if (ret)
+ return ret;
+ }
+
+ usleep_range(700, 1000);
+
+ return ret;
+}
+
static int regmap_spi_gather_write(void *context, const void *reg,
size_t reg_len, const void *val,
size_t val_len)
@@ -341,6 +363,7 @@ static int tcan4x5x_init(struct m_can_classdev *cdev)
static int tcan4x5x_parse_config(struct m_can_classdev *cdev)
{
struct tcan4x5x_priv *tcan4x5x = cdev->device_data;
+ int ret;

tcan4x5x->device_wake_gpio = devm_gpiod_get(cdev->dev, "device-wake",
GPIOD_OUT_HIGH);
@@ -354,7 +377,9 @@ static int tcan4x5x_parse_config(struct m_can_classdev *cdev)
if (IS_ERR(tcan4x5x->reset_gpio))
tcan4x5x->reset_gpio = NULL;

- usleep_range(700, 1000);
+ ret = tcan4x5x_reset(tcan4x5x);
+ if (ret)
+ return ret;

tcan4x5x->device_state_gpio = devm_gpiod_get_optional(cdev->dev,
"device-state",
--
2.20.1