[PATCH v3 1/3] power: reset: add linkstation-reset driver

[Roger Shimizu <rogershimizu@gmail.com>]

Buffalo Linkstation / KuroBox and their variants need magic command
sending to UART1 to power-off.

Power driver linkstation-reset implements the magic command and I/O
routine, which come from files listed below:
  - arch/arm/mach-orion5x/kurobox_pro-setup.c
  - arch/arm/mach-orion5x/terastation_pro2-setup.c

To: Sebastian Reichel <sre@kernel.org>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Martin Michlmayr <tbm@cyrius.com>
Cc: Sylver Bruneau <sylver.bruneau@googlemail.com>
Cc: Herbert Valerio Riedel <hvr@gnu.org>
Cc: Ryan Tandy <ryan@nardis.ca>
Cc: linux-pm@vger.kernel.org
Cc: devicetree@vger.kernel.org
Cc: linux-arm-kernel@lists.infradead.org

Reported-by: Ryan Tandy <ryan@nardis.ca>
Tested-by: Ryan Tandy <ryan@nardis.ca>
Signed-off-by: Roger Shimizu <rogershimizu@gmail.com>
---
 drivers/power/reset/Kconfig             |  10 ++
 drivers/power/reset/Makefile            |   1 +
 drivers/power/reset/linkstation-reset.c | 269 ++++++++++++++++++++++++++++++++
 3 files changed, 280 insertions(+)
 create mode 100644 drivers/power/reset/linkstation-reset.c

diff --git a/drivers/power/reset/Kconfig b/drivers/power/reset/Kconfig
index c74c3f67b8da..77c44cad7ece 100644
--- a/drivers/power/reset/Kconfig
+++ b/drivers/power/reset/Kconfig
@@ -98,6 +98,16 @@ config POWER_RESET_IMX
 	  say N here or disable in dts to make sure pm_power_off never be
 	  overwrote wrongly by this driver.
 
+config POWER_RESET_LINKSTATION
+	bool "Buffalo Linkstation and its variants reset driver"
+	depends on OF_GPIO && PLAT_ORION
+	help
+	  This driver supports power off Buffalo Linkstation / KuroBox Pro
+	  NAS and their variants by sending commands to the micro-controller
+	  which controls the main power.
+
+	  Say Y if you have a Buffalo Linkstation / KuroBox Pro NAS.
+
 config POWER_RESET_MSM
 	bool "Qualcomm MSM power-off driver"
 	depends on ARCH_QCOM
diff --git a/drivers/power/reset/Makefile b/drivers/power/reset/Makefile
index 1be307c7fc25..692ba6417cfb 100644
--- a/drivers/power/reset/Makefile
+++ b/drivers/power/reset/Makefile
@@ -9,6 +9,7 @@ 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_IMX) += imx-snvs-poweroff.o
+obj-$(CONFIG_POWER_RESET_LINKSTATION) += linkstation-reset.o
 obj-$(CONFIG_POWER_RESET_MSM) += msm-poweroff.o
 obj-$(CONFIG_POWER_RESET_LTC2952) += ltc2952-poweroff.o
 obj-$(CONFIG_POWER_RESET_QNAP) += qnap-poweroff.o
diff --git a/drivers/power/reset/linkstation-reset.c b/drivers/power/reset/linkstation-reset.c
new file mode 100644
index 000000000000..4390495dfe0e
--- /dev/null
+++ b/drivers/power/reset/linkstation-reset.c
@@ -0,0 +1,269 @@
+/*
+ * Buffalo Linkstation power reset driver.
+ * It may also be used on following devices:
+ *  - KuroBox Pro
+ *  - Buffalo Linkstation Pro (LS-GL)
+ *  - Buffalo Terastation Pro II/Live
+ *  - Buffalo Linkstation Duo (LS-WTGL)
+ *  - Buffalo Linkstation Mini (LS-WSGL)
+ *
+ * Copyright (C) 2016  Roger Shimizu <rogershimizu@gmail.com>
+ *
+ * Based on the code from:
+ *
+ * Copyright (C) 2012  Andrew Lunn <andrew@lunn.ch>
+ * Copyright (C) 2009  Martin Michlmayr <tbm@cyrius.com>
+ * Copyright (C) 2008  Byron Bradley <byron.bbradley@gmail.com>
+ * Copyright (C) 2008  Sylver Bruneau <sylver.bruneau@googlemail.com>
+ * Copyright (C) 2007  Herbert Valerio Riedel <hvr@gnu.org>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/serial_reg.h>
+#include <linux/kallsyms.h>
+#include <linux/of.h>
+#include <linux/io.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+
+#define UART1_REG(x)	(base + ((UART_##x) << 2))
+#define MICON_CMD_SIZE	4
+
+/* 4-byte magic hello command to UART1-attached microcontroller */
+static const unsigned char linkstation_micon_magic[] = {
+	0x1b,
+	0x00,
+	0x07,
+	0x00
+};
+
+/* for each row, first byte is the size of command */
+static const unsigned char linkstation_power_off_cmd[][MICON_CMD_SIZE] = {
+	{ 3,	0x01, 0x35, 0x00},
+	{ 2,	0x00, 0x0c},
+	{ 2,	0x00, 0x06},
+	{}
+};
+
+struct reset_cfg {
+	u32 baud;
+	const unsigned char *magic;
+	const unsigned char (*cmd)[MICON_CMD_SIZE];
+};
+
+static const struct reset_cfg linkstation_power_off_cfg = {
+	.baud = 38400,
+	.magic = linkstation_micon_magic,
+	.cmd = linkstation_power_off_cmd,
+};
+
+static const struct of_device_id linkstation_reset_of_match_table[] = {
+	{ .compatible = "linkstation,power-off",
+	  .data = &linkstation_power_off_cfg,
+	},
+	{}
+};
+MODULE_DEVICE_TABLE(of, linkstation_reset_of_match_table);
+
+static int uart1_micon_read(void *base, unsigned char *buf, int count)
+{
+	int i;
+	int timeout;
+
+	for (i = 0; i < count; i++) {
+		timeout = 10;
+
+		while (!(readl(UART1_REG(LSR)) & UART_LSR_DR)) {
+			if (--timeout == 0)
+				break;
+			udelay(1000);
+		}
+
+		if (timeout == 0)
+			break;
+		buf[i] = readl(UART1_REG(RX));
+	}
+
+	/* return read bytes */
+	return i;
+}
+
+static int uart1_micon_write(void *base, const unsigned char *buf, int count)
+{
+	int i = 0;
+
+	while (count--) {
+		while (!(readl(UART1_REG(LSR)) & UART_LSR_THRE))
+			barrier();
+		writel(buf[i++], UART1_REG(TX));
+	}
+
+	return 0;
+}
+
+int uart1_micon_send(void *base, const unsigned char *data, int count)
+{
+	int i;
+	unsigned char checksum = 0;
+	unsigned char recv_buf[40];
+	unsigned char send_buf[40];
+	unsigned char correct_ack[3];
+	int retry = 2;
+
+	/* Generate checksum */
+	for (i = 0; i < count; i++)
+		checksum -=  data[i];
+
+	do {
+		/* Send data */
+		uart1_micon_write(base, data, count);
+
+		/* send checksum */
+		uart1_micon_write(base, &checksum, 1);
+
+		if (uart1_micon_read(base, recv_buf, sizeof(recv_buf)) <= 3) {
+			printk(KERN_ERR ">%s: receive failed.\n", __func__);
+
+			/* send preamble to clear the receive buffer */
+			memset(&send_buf, 0xff, sizeof(send_buf));
+			uart1_micon_write(base, send_buf, sizeof(send_buf));
+
+			/* make dummy reads */
+			mdelay(100);
+			uart1_micon_read(base, recv_buf, sizeof(recv_buf));
+		} else {
+			/* Generate expected ack */
+			correct_ack[0] = 0x01;
+			correct_ack[1] = data[1];
+			correct_ack[2] = 0x00;
+
+			/* checksum Check */
+			if ((recv_buf[0] + recv_buf[1] + recv_buf[2] +
+			     recv_buf[3]) & 0xFF) {
+				printk(KERN_ERR ">%s: Checksum Error : "
+					"Received data[%02x, %02x, %02x, %02x]"
+					"\n", __func__, recv_buf[0],
+					recv_buf[1], recv_buf[2], recv_buf[3]);
+			} else {
+				/* Check Received Data */
+				if (correct_ack[0] == recv_buf[0] &&
+				    correct_ack[1] == recv_buf[1] &&
+				    correct_ack[2] == recv_buf[2]) {
+					/* Interval for next command */
+					mdelay(10);
+
+					/* Receive ACK */
+					return 0;
+				}
+			}
+			/* Received NAK or illegal Data */
+			printk(KERN_ERR ">%s: Error : NAK or Illegal Data "
+					"Received\n", __func__);
+		}
+	} while (retry--);
+
+	/* Interval for next command */
+	mdelay(10);
+
+	return -1;
+}
+
+static void __iomem *base;
+static unsigned long tclk;
+static const struct reset_cfg *cfg;
+
+static void linkstation_reset(void)
+{
+	const unsigned divisor = ((tclk + (8 * cfg->baud)) / (16 * cfg->baud));
+	int i;
+
+	pr_err("%s: triggering power-off...\n", __func__);
+
+	/* hijack UART1 and reset into sane state */
+	writel(0x83, UART1_REG(LCR));
+	writel(divisor & 0xff, UART1_REG(DLL));
+	writel((divisor >> 8) & 0xff, UART1_REG(DLM));
+	writel(cfg->magic[0], UART1_REG(LCR));
+	writel(cfg->magic[1], UART1_REG(IER));
+	writel(cfg->magic[2], UART1_REG(FCR));
+	writel(cfg->magic[3], UART1_REG(MCR));
+
+	/* send the power-off command to PIC */
+	for(i = 0; cfg->cmd[i][0] > 0; i ++) {
+		/* [0] is size of the command; command starts from [1] */
+		uart1_micon_send(base, &(cfg->cmd[i][1]), cfg->cmd[i][0]);
+	}
+}
+
+static int linkstation_reset_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct resource *res;
+	struct clk *clk;
+	char symname[KSYM_NAME_LEN];
+
+	const struct of_device_id *match =
+		of_match_node(linkstation_reset_of_match_table, np);
+	cfg = match->data;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		dev_err(&pdev->dev, "Missing resource");
+		return -EINVAL;
+	}
+
+	base = devm_ioremap(&pdev->dev, res->start, resource_size(res));
+	if (!base) {
+		dev_err(&pdev->dev, "Unable to map resource");
+		return -EINVAL;
+	}
+
+	/* We need to know tclk in order to calculate the UART divisor */
+	clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "Clk missing");
+		return PTR_ERR(clk);
+	}
+
+	tclk = clk_get_rate(clk);
+
+	/* Check that nothing else has already setup a handler */
+	if (pm_power_off) {
+		lookup_symbol_name((ulong)pm_power_off, symname);
+		dev_err(&pdev->dev,
+			"pm_power_off already claimed %p %s",
+			pm_power_off, symname);
+		return -EBUSY;
+	}
+	pm_power_off = linkstation_reset;
+
+	return 0;
+}
+
+static int linkstation_reset_remove(struct platform_device *pdev)
+{
+	pm_power_off = NULL;
+	return 0;
+}
+
+static struct platform_driver linkstation_reset_driver = {
+	.probe	= linkstation_reset_probe,
+	.remove	= linkstation_reset_remove,
+	.driver	= {
+		.name	= "linkstation_reset",
+		.of_match_table = of_match_ptr(linkstation_reset_of_match_table),
+	},
+};
+
+module_platform_driver(linkstation_reset_driver);
+
+MODULE_AUTHOR("Roger Shimizu <rogershimizu@gmail.com>");
+MODULE_DESCRIPTION("Linkstation Reset driver");
+MODULE_LICENSE("GPL v2");
-- 
2.11.0