phy: phy-can-transceiver: Add support for generic CAN transceiver driver

The driver adds support for generic CAN transceivers. Currently
the modes supported by this driver are standby and normal modes for TI
TCAN1042 and TCAN1043 CAN transceivers.

The transceiver is modelled as a phy with pins controlled by gpios, to put
the transceiver in various device functional modes. It also gets the phy
attribute max_link_rate for the usage of CAN drivers.

Signed-off-by: Aswath Govindraju <a-govindraju@ti.com>
Acked-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/20210510051006.11393-4-a-govindraju@ti.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 146 insertions, 0 deletions

diff --git a/drivers/phy/phy-can-transceiver.c b/drivers/phy/phy-can-transceiver.c
new file mode 100644
index 000000000000..c2cb93b4df71
--- /dev/null
+++ b/drivers/phy/phy-can-transceiver.c
@@ -0,0 +1,146 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * phy-can-transceiver.c - phy driver for CAN transceivers
+ *
+ * Copyright (C) 2021 Texas Instruments Incorporated - https://www.ti.com
+ *
+ */
+#include<linux/phy/phy.h>
+#include<linux/platform_device.h>
+#include<linux/module.h>
+#include<linux/gpio.h>
+#include<linux/gpio/consumer.h>
+
+struct can_transceiver_data {
+	u32 flags;
+#define CAN_TRANSCEIVER_STB_PRESENT	BIT(0)
+#define CAN_TRANSCEIVER_EN_PRESENT	BIT(1)
+};
+
+struct can_transceiver_phy {
+	struct phy *generic_phy;
+	struct gpio_desc *standby_gpio;
+	struct gpio_desc *enable_gpio;
+};
+
+/* Power on function */
+static int can_transceiver_phy_power_on(struct phy *phy)
+{
+	struct can_transceiver_phy *can_transceiver_phy = phy_get_drvdata(phy);
+
+	if (can_transceiver_phy->standby_gpio)
+		gpiod_set_value_cansleep(can_transceiver_phy->standby_gpio, 0);
+	if (can_transceiver_phy->enable_gpio)
+		gpiod_set_value_cansleep(can_transceiver_phy->enable_gpio, 1);
+
+	return 0;
+}
+
+/* Power off function */
+static int can_transceiver_phy_power_off(struct phy *phy)
+{
+	struct can_transceiver_phy *can_transceiver_phy = phy_get_drvdata(phy);
+
+	if (can_transceiver_phy->standby_gpio)
+		gpiod_set_value_cansleep(can_transceiver_phy->standby_gpio, 1);
+	if (can_transceiver_phy->enable_gpio)
+		gpiod_set_value_cansleep(can_transceiver_phy->enable_gpio, 0);
+
+	return 0;
+}
+
+static const struct phy_ops can_transceiver_phy_ops = {
+	.power_on	= can_transceiver_phy_power_on,
+	.power_off	= can_transceiver_phy_power_off,
+	.owner		= THIS_MODULE,
+};
+
+static const struct can_transceiver_data tcan1042_drvdata = {
+	.flags = CAN_TRANSCEIVER_STB_PRESENT,
+};
+
+static const struct can_transceiver_data tcan1043_drvdata = {
+	.flags = CAN_TRANSCEIVER_STB_PRESENT | CAN_TRANSCEIVER_EN_PRESENT,
+};
+
+static const struct of_device_id can_transceiver_phy_ids[] = {
+	{
+		.compatible = "ti,tcan1042",
+		.data = &tcan1042_drvdata
+	},
+	{
+		.compatible = "ti,tcan1043",
+		.data = &tcan1043_drvdata
+	},
+	{ }
+};
+MODULE_DEVICE_TABLE(of, can_transceiver_phy_ids);
+
+static int can_transceiver_phy_probe(struct platform_device *pdev)
+{
+	struct phy_provider *phy_provider;
+	struct device *dev = &pdev->dev;
+	struct can_transceiver_phy *can_transceiver_phy;
+	const struct can_transceiver_data *drvdata;
+	const struct of_device_id *match;
+	struct phy *phy;
+	struct gpio_desc *standby_gpio;
+	struct gpio_desc *enable_gpio;
+	u32 max_bitrate = 0;
+
+	can_transceiver_phy = devm_kzalloc(dev, sizeof(struct can_transceiver_phy), GFP_KERNEL);
+	if (!can_transceiver_phy)
+		return -ENOMEM;
+
+	match = of_match_node(can_transceiver_phy_ids, pdev->dev.of_node);
+	drvdata = match->data;
+
+	phy = devm_phy_create(dev, dev->of_node,
+			      &can_transceiver_phy_ops);
+	if (IS_ERR(phy)) {
+		dev_err(dev, "failed to create can transceiver phy\n");
+		return PTR_ERR(phy);
+	}
+
+	device_property_read_u32(dev, "max-bitrate", &max_bitrate);
+	if (!max_bitrate)
+		dev_warn(dev, "Invalid value for transceiver max bitrate. Ignoring bitrate limit\n");
+	phy->attrs.max_link_rate = max_bitrate;
+
+	can_transceiver_phy->generic_phy = phy;
+
+	if (drvdata->flags & CAN_TRANSCEIVER_STB_PRESENT) {
+		standby_gpio = devm_gpiod_get(dev, "standby", GPIOD_OUT_HIGH);
+		if (IS_ERR(standby_gpio))
+			return PTR_ERR(standby_gpio);
+		can_transceiver_phy->standby_gpio = standby_gpio;
+	}
+
+	if (drvdata->flags & CAN_TRANSCEIVER_EN_PRESENT) {
+		enable_gpio = devm_gpiod_get(dev, "enable", GPIOD_OUT_LOW);
+		if (IS_ERR(enable_gpio))
+			return PTR_ERR(enable_gpio);
+		can_transceiver_phy->enable_gpio = enable_gpio;
+	}
+
+	phy_set_drvdata(can_transceiver_phy->generic_phy, can_transceiver_phy);
+
+	phy_provider = devm_of_phy_provider_register(dev, of_phy_simple_xlate);
+
+	return PTR_ERR_OR_ZERO(phy_provider);
+}
+
+static struct platform_driver can_transceiver_phy_driver = {
+	.probe = can_transceiver_phy_probe,
+	.driver = {
+		.name = "can-transceiver-phy",
+		.of_match_table = can_transceiver_phy_ids,
+	},
+};
+
+module_platform_driver(can_transceiver_phy_driver);
+
+MODULE_AUTHOR("Faiz Abbas <faiz_abbas@ti.com>");
+MODULE_AUTHOR("Aswath Govindraju <a-govindraju@ti.com>");
+MODULE_DESCRIPTION("CAN TRANSCEIVER PHY driver");
+MODULE_LICENSE("GPL v2");