can: mcp251xfd: add support for XSTBYEN transceiver standby control

The MCP251xFD has a dedicated transceiver standby control function on
the INT0/GPIO0/XSTBY pin, controlled by the XSTBYEN bit in IOCON.
When enabled, the hardware automatically manages the transceiver
standby state: the pin is driven low when the controller is active
and high when it enters Sleep mode.

Enable this feature when the 'microchip,xstbyen' device tree property
is present.

Signed-off-by: Viken Dadhaniya <viken.dadhaniya@oss.qualcomm.com>
Link: https://patch.msgid.link/20260321135031.3107408-3-viken.dadhaniya@oss.qualcomm.com
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
index 9c86df08c2c53595806157daa675ebd7b0309fe7..92a86083c8962161cf1bd442ddb1ef72b12faf21 100644 (file)
--- a/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd-core.c
@@ -764,6 +764,31 @@ static void mcp251xfd_chip_stop(struct mcp251xfd_priv *priv,
        mcp251xfd_chip_set_mode(priv, MCP251XFD_REG_CON_MODE_CONFIG);
 }
 
+static int mcp251xfd_chip_xstbyen_enable(const struct mcp251xfd_priv *priv)
+{
+       /* Configure the INT0/GPIO0/XSTBY pin as transceiver standby control:
+        *
+        * - XSTBYEN=1: route the pin to the transceiver standby function
+        * - TRIS0=0:   set output direction; the reset default is 1 (input),
+        *              which leaves the pin floating HIGH and keeps the
+        *              transceiver in standby regardless of XSTBYEN
+        * - LAT0=0:    drive pin LOW => transceiver active (not in standby)
+        *
+        * All three bits are included in the mask; only XSTBYEN is set in
+        * val, so TRIS0 and LAT0 are cleared to 0 atomically.
+        *
+        * Pin behaviour by mode:
+        * - Config mode: controlled by LAT0 (LAT0=0 => LOW => active)
+        * - Normal mode: hardware drives pin LOW (active)
+        * - Sleep mode:  hardware drives pin HIGH (standby)
+        */
+       return regmap_update_bits(priv->map_reg, MCP251XFD_REG_IOCON,
+                                 MCP251XFD_REG_IOCON_XSTBYEN |
+                                 MCP251XFD_REG_IOCON_TRIS0 |
+                                 MCP251XFD_REG_IOCON_LAT0,
+                                 MCP251XFD_REG_IOCON_XSTBYEN);
+}
+
 static int mcp251xfd_chip_start(struct mcp251xfd_priv *priv)
 {
        int err;
@@ -796,6 +821,12 @@ static int mcp251xfd_chip_start(struct mcp251xfd_priv *priv)
 
        priv->can.state = CAN_STATE_ERROR_ACTIVE;
 
+       if (priv->xstbyen) {
+               err = mcp251xfd_chip_xstbyen_enable(priv);
+               if (err)
+                       goto out_chip_stop;
+       }
+
        err = mcp251xfd_chip_set_normal_mode(priv);
        if (err)
                goto out_chip_stop;
@@ -1805,6 +1836,11 @@ static int mcp251xfd_gpio_request(struct gpio_chip *chip, unsigned int offset)
        u32 pin_mask = MCP251XFD_REG_IOCON_PM(offset);
        int ret;
 
+       if (priv->xstbyen && offset == 0) {
+               netdev_err(priv->ndev, "Can't use GPIO 0 with XSTBYEN!\n");
+               return -EINVAL;
+       }
+
        if (priv->rx_int && offset == 1) {
                netdev_err(priv->ndev, "Can't use GPIO 1 with RX-INT!\n");
                return -EINVAL;
@@ -2271,6 +2307,7 @@ static int mcp251xfd_probe(struct spi_device *spi)
        priv->pll_enable = pll_enable;
        priv->reg_vdd = reg_vdd;
        priv->reg_xceiver = reg_xceiver;
+       priv->xstbyen = device_property_present(&spi->dev, "microchip,xstbyen");
        priv->devtype_data = *(struct mcp251xfd_devtype_data *)spi_get_device_match_data(spi);
 
        /* Errata Reference:

diff --git a/drivers/net/can/spi/mcp251xfd/mcp251xfd.h b/drivers/net/can/spi/mcp251xfd/mcp251xfd.h
index 085d7101e595ed8463f4d85c98e2a9e975f0f648..d3f4704e26780134e9cde7fce100333f3fb76a79 100644 (file)
--- a/drivers/net/can/spi/mcp251xfd/mcp251xfd.h
+++ b/drivers/net/can/spi/mcp251xfd/mcp251xfd.h
@@ -672,6 +672,7 @@ struct mcp251xfd_priv {
        struct gpio_desc *rx_int;
        struct clk *clk;
        bool pll_enable;
+       bool xstbyen;
        struct regulator *reg_vdd;
        struct regulator *reg_xceiver;