net: pse-pd: tps23881: Support reset-gpios

The TPS23880/1 has an active-low reset pin that some boards connect to
the SoC to control when the TPS23880 is pulled out of reset.

Add support for this via a reset-gpios property in the DTS.

Signed-off-by: Kyle Swenson <kyle.swenson@est.tech>
Acked-by: Oleksij Rempel <o.rempel@pengutronix.de>
Reviewed-by: Kory Maincent <kory.maincent@bootlin.com>
Link: https://patch.msgid.link/20240822220100.3030184-3-kyle.swenson@est.tech
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/pse-pd/tps23881.c b/drivers/net/pse-pd/tps23881.c
index 2ea75686a3190730aed82045ef113db3abafdca0..5c4e88be46ee3316330e26a68d06540ff1db86ff 100644 (file)
--- a/drivers/net/pse-pd/tps23881.c
+++ b/drivers/net/pse-pd/tps23881.c
@@ -8,6 +8,7 @@
 #include <linux/bitfield.h>
 #include <linux/delay.h>
 #include <linux/firmware.h>
+#include <linux/gpio/consumer.h>
 #include <linux/i2c.h>
 #include <linux/module.h>
 #include <linux/of.h>
@@ -737,6 +738,7 @@ static int tps23881_i2c_probe(struct i2c_client *client)
 {
        struct device *dev = &client->dev;
        struct tps23881_priv *priv;
+       struct gpio_desc *reset;
        int ret;
        u8 val;
 
@@ -749,6 +751,25 @@ static int tps23881_i2c_probe(struct i2c_client *client)
        if (!priv)
                return -ENOMEM;
 
+       reset = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+       if (IS_ERR(reset))
+               return dev_err_probe(&client->dev, PTR_ERR(reset), "Failed to get reset GPIO\n");
+
+       if (reset) {
+               /* TPS23880 datasheet (Rev G) indicates minimum reset pulse is 5us */
+               usleep_range(5, 10);
+               gpiod_set_value_cansleep(reset, 0); /* De-assert reset */
+
+               /* TPS23880 datasheet indicates the minimum time after power on reset
+                * should be 20ms, but the document describing how to load SRAM ("How
+                * to Load TPS2388x SRAM and Parity Code over I2C" (Rev E))
+                * indicates we should delay that programming by at least 50ms. So
+                * we'll wait the entire 50ms here to ensure we're safe to go to the
+                * SRAM loading proceedure.
+                */
+               msleep(50);
+       }
+
        ret = i2c_smbus_read_byte_data(client, TPS23881_REG_DEVID);
        if (ret < 0)
                return ret;