[PATCH 1/2] power:reset: add driver for LinkStation power off

["Daniel González Cabanelas" <dgcbueu@gmail.com>]

Some Buffalo LinkStations perform the power off operation, at restart
time, depending on the state of an output pin (LED) at the ethernet PHY.

The driver is required by the Buffalo LinkStation LS421DE (ARM MVEBU),
and other models. Without it, the board remains forever halted if a 
power off command is executed, unless the PSU is disconnected and
connected again.

Signed-off-by: Daniel González Cabanelas <dgcbueu@gmail.com>
Reviewed-by: Álvaro Fernández Rojas <noltari@gmail.com>
---
 drivers/power/reset/Kconfig                |  10 ++
 drivers/power/reset/Makefile               |   1 +
 drivers/power/reset/linkstation-poweroff.c | 117 +++++++++++++++++++++
 3 files changed, 128 insertions(+)
 create mode 100644 drivers/power/reset/linkstation-poweroff.c

diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index 8903803020..de948835f8 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -203,6 +203,16 @@ config POWER_RESET_KEYSTONE
 	help
 	  Reboot support for the KEYSTONE SoCs.
 
+config POWER_RESET_LINKSTATION
+	tristate "Buffalo LinkStation power-off driver"
+	depends on ARCH_MVEBU || COMPILE_TEST
+	depends on OF_MDIO && PHYLIB
+	help
+	  Some Buffalo LinkStations use a LED output at the ethernet PHY
+	  to inform the board that a power off operation must be performed 
+	  after restarting. This driver sets the LED to the proper state
+	  for restarting or powering off.
+
 config POWER_RESET_SYSCON
 	bool "Generic SYSCON regmap reset driver"
 	depends on OF
diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index da37f8b851..a8c83d2470 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile
@@ -10,6 +10,7 @@ obj-$(CONFIG_POWER_RESET_GEMINI_POWEROFF) += gemini-poweroff.o
 obj-$(CONFIG_POWER_RESET_GPIO) += gpio-poweroff.o
 obj-$(CONFIG_POWER_RESET_GPIO_RESTART) += gpio-restart.o
 obj-$(CONFIG_POWER_RESET_HISI) += hisi-reboot.o
+obj-${CONFIG_POWER_RESET_LINKSTATION} += linkstation-poweroff.o
 obj-$(CONFIG_POWER_RESET_MSM) += msm-poweroff.o
 obj-$(CONFIG_POWER_RESET_MT6323) += mt6323-poweroff.o
 obj-$(CONFIG_POWER_RESET_QCOM_PON) += qcom-pon.o
diff --git a/drivers/power/reset/linkstation-poweroff.c b/drivers/power/reset/linkstation-poweroff.c
new file mode 100644
index 0000000000..b5a4cc2c2b
--- /dev/null
+++ b/drivers/power/reset/linkstation-poweroff.c
@@ -0,0 +1,117 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * LinkStation power off restart driver
+ * Copyright (C) 2020 Daniel González Cabanelas <dgcbueu@gmail.com>
+ */
+
+#include <linux/module.h>
+#include <linux/notifier.h>
+#include <linux/of.h>
+#include <linux/of_mdio.h>
+#include <linux/of_platform.h>
+#include <linux/reboot.h>
+#include <linux/phy.h>
+
+#define MII_MARVELL_LED_PAGE	3
+#define MII_PHY_LED_CTRL	16
+
+#define LED2_OFF		(0x8 << 8)
+#define LED2_ON			(0x9 << 8)
+#define LEDMASK			GENMASK(11,8)
+
+static struct phy_device *phydev;
+
+static void mvphy_reg_led(u16 data)
+{
+	int rc;
+	rc = phy_modify_paged(phydev, MII_MARVELL_LED_PAGE,
+			      MII_PHY_LED_CTRL, LEDMASK, data);
+	if (rc < 0)
+		dev_err(&phydev->mdio.dev,
+			"LED2 write register failed, %d\n", rc);
+}
+
+static int linkstation_reboot_notifier(struct notifier_block *nb,
+				       unsigned long action, void *unused)
+{
+	if (action == SYS_RESTART)
+		mvphy_reg_led(LED2_ON);
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block linkstation_reboot_nb = {
+	.notifier_call = linkstation_reboot_notifier,
+};
+
+static void linkstation_poweroff(void)
+{
+	unregister_reboot_notifier(&linkstation_reboot_nb);
+	mvphy_reg_led(LED2_OFF);
+
+	kernel_restart("Power off");
+}
+
+static int linkstation_poweroff_probe(struct platform_device *pdev)
+{
+	struct mii_bus *bus;
+	struct device_node *dn;
+
+	dn = of_parse_phandle(pdev->dev.of_node, "phy-handle,led", 0);
+
+	if (dn) {
+		phydev = of_phy_find_device(dn);
+		of_node_put(dn);
+	} else {
+		dn = of_find_node_by_name(NULL, "mdio");
+		if (!dn)
+			return -ENODEV;
+
+		bus = of_mdio_find_bus(dn);
+		of_node_put(dn);
+		if (!bus)
+			return -EPROBE_DEFER;
+
+		phydev = phy_find_first(bus);
+	}
+
+	if (!phydev)
+		return -ENODEV;
+
+	register_reboot_notifier(&linkstation_reboot_nb);
+	pm_power_off = linkstation_poweroff;
+
+	dev_info(&pdev->dev, "PHY [%s]\n", phydev_name(phydev));
+
+	return 0;
+}
+
+static int linkstation_poweroff_remove(struct platform_device *pdev)
+{
+	pm_power_off = NULL;
+	unregister_reboot_notifier(&linkstation_reboot_nb);
+
+	return 0;
+}
+
+static const struct of_device_id ls_poweroff_of_match[] = {
+	{ .compatible = "linkstation,power-off", },
+	{ },
+};
+
+MODULE_DEVICE_TABLE(of, ls_poweroff_of_match);
+
+static struct platform_driver linkstation_poweroff_driver = {
+	.probe = linkstation_poweroff_probe,
+	.remove = linkstation_poweroff_remove,
+	.driver = {
+		.name = "linkstation_power_off",
+		.of_match_table = ls_poweroff_of_match,
+	},
+};
+
+module_platform_driver(linkstation_poweroff_driver);
+
+MODULE_AUTHOR("Daniel González Cabanelas <dgcbueu@gmail.com>");
+MODULE_DESCRIPTION("LinkStation power off driver");
+MODULE_LICENSE("GPL v2");
-- 
2.26.2