Message-Id: <20161229000137.5553-2-f.fainelli@gmail.com>
Date:   Wed, 28 Dec 2016 16:01:36 -0800
From:   Florian Fainelli <f.fainelli@...il.com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     lee.jones@...aro.org, linux@...linux.org.uk,
        gregory.clement@...e-electrons.com, andrew@...n.ch,
        jason@...edaemon.net, linux-kernel@...r.kernel.org,
        Florian Fainelli <f.fainelli@...il.com>
Subject: [PATCH 1/2] mfd: micon: Add Buffalo Kurobox Pro, Terastation II Pro/Live driver

This driver is currently only used to reboot the devices, but the
microcontroller hanging off UART1 on the Buffalo Kurobox Pro and
Terastation II Pro/Live is capable of a lot more than that, which we
will support in subsequent patches. For now, just add the reboot
functionality to make the kernel reboot correctly.

Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
---
 drivers/mfd/Kconfig                 |   8 ++
 drivers/mfd/Makefile                |   2 +
 drivers/mfd/micon.c                 | 204 ++++++++++++++++++++++++++++++++++++
 include/linux/platform_data/micon.h |  10 ++
 4 files changed, 224 insertions(+)
 create mode 100644 drivers/mfd/micon.c
 create mode 100644 include/linux/platform_data/micon.h

diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
index 4ce3b6f11830..e7df3d29351c 100644
--- a/drivers/mfd/Kconfig
+++ b/drivers/mfd/Kconfig
@@ -352,6 +352,14 @@ config MFD_MX25_TSADC
 	  i.MX25 processors. They consist of a conversion queue for general
 	  purpose ADC and a queue for Touchscreens.
 
+config MFD_MICON
+	bool "Buffalo Kurobox Pro/Terastation II Pro/Live MCU interface"
+	depends on PLAT_ORION
+	help
+	  Enables support for the UART1 attached micro controller on Buffalo
+	  Kurobox Pro and Terastation II Pro/Live NAS devices. Used for
+	  machine restart.
+
 config MFD_HI6421_PMIC
 	tristate "HiSilicon Hi6421 PMU/Codec IC"
 	depends on OF
diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
index dda4d4f73ad7..61a226878129 100644
--- a/drivers/mfd/Makefile
+++ b/drivers/mfd/Makefile
@@ -94,6 +94,8 @@ obj-$(CONFIG_MFD_MC13XXX)	+= mc13xxx-core.o
 obj-$(CONFIG_MFD_MC13XXX_SPI)	+= mc13xxx-spi.o
 obj-$(CONFIG_MFD_MC13XXX_I2C)	+= mc13xxx-i2c.o
 
+obj-$(CONFIG_MFD_MICON)		+= micon.o
+
 obj-$(CONFIG_MFD_CORE)		+= mfd-core.o
 
 obj-$(CONFIG_EZX_PCAP)		+= ezx-pcap.o
diff --git a/drivers/mfd/micon.c b/drivers/mfd/micon.c
new file mode 100644
index 000000000000..fe56abdc0160
--- /dev/null
+++ b/drivers/mfd/micon.c
@@ -0,0 +1,204 @@
+/*
+ * Buffalo Kurobox/Terastation Pro II specific power off method via
+ * UART1-attached microcontroller
+ *
+ * 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/io.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/platform_data/micon.h>
+#include <linux/serial_reg.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
+
+struct micon_priv {
+	struct device *dev;
+	void __iomem *base;
+	int tclk;
+	struct notifier_block nb;
+};
+
+#define UART1_REG(x)	((UART_##x) << 2)
+
+static int miconread(struct micon_priv *priv, unsigned char *buf, int count)
+{
+	int i;
+	int timeout;
+
+	for (i = 0; i < count; i++) {
+		timeout = 10;
+
+		while (!(readl(priv->base + UART1_REG(LSR)) & UART_LSR_DR)) {
+			if (--timeout == 0)
+				break;
+			udelay(1000);
+		}
+
+		if (timeout == 0)
+			break;
+		buf[i] = readl(priv->base + UART1_REG(RX));
+	}
+
+	/* return read bytes */
+	return i;
+}
+
+static int miconwrite(struct micon_priv *priv, const unsigned char *buf,
+			   int count)
+{
+	int i = 0;
+
+	while (count--) {
+		while (!(readl(priv->base + UART1_REG(LSR)) & UART_LSR_THRE))
+			barrier();
+		writel(buf[i++], priv->base + UART1_REG(TX));
+	}
+
+	return 0;
+}
+
+static int miconsend(struct micon_priv *priv, 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 */
+		miconwrite(priv, data, count);
+
+		/* send checksum */
+		miconwrite(priv, &checksum, 1);
+
+		if (miconread(priv, recv_buf, sizeof(recv_buf)) <= 3) {
+			dev_err(priv->dev, ">%s: receive failed.\n", __func__);
+
+			/* send preamble to clear the receive buffer */
+			memset(&send_buf, 0xff, sizeof(send_buf));
+			miconwrite(priv, send_buf, sizeof(send_buf));
+
+			/* make dummy reads */
+			mdelay(100);
+			miconread(priv, 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) {
+				dev_err(priv->dev, ">%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 */
+			dev_err(priv->dev, ">%s: Error : NAK or Illegal Data "
+					    "Received\n", __func__);
+		}
+	} while (retry--);
+
+	/* Interval for next command */
+	mdelay(10);
+
+	return -1;
+}
+
+static int restart_handler(struct notifier_block *this,
+			   unsigned long code, void *cmd)
+{
+	struct micon_priv *priv = container_of(this, struct micon_priv, nb);
+
+	const unsigned char watchdogkill[]	= {0x01, 0x35, 0x00};
+	const unsigned char shutdownwait[]	= {0x00, 0x0c};
+	const unsigned char poweroff[]		= {0x00, 0x06};
+	/* 38400 baud divisor */
+	unsigned int divisor = ((priv->tclk + (8 * 38400)) / (16 * 38400));
+
+	if (code != SYS_DOWN && code != SYS_HALT)
+		return NOTIFY_DONE;
+
+	dev_info(priv->dev, "%s: triggering power-off...\n", __func__);
+
+	/* hijack uart1 and reset into sane state (38400,8n1,even parity) */
+	writel(0x83, priv->base + UART1_REG(LCR));
+	writel(divisor & 0xff, priv->base + UART1_REG(DLL));
+	writel((divisor >> 8) & 0xff, priv->base + UART1_REG(DLM));
+	writel(0x1b, priv->base + UART1_REG(LCR));
+	writel(0x00, priv->base + UART1_REG(IER));
+	writel(0x07, priv->base + UART1_REG(FCR));
+	writel(0x00, priv->base + UART1_REG(MCR));
+
+	/* Send the commands to shutdown the Terastation Pro II */
+	miconsend(priv, watchdogkill, sizeof(watchdogkill));
+	miconsend(priv, shutdownwait, sizeof(shutdownwait));
+	miconsend(priv, poweroff, sizeof(poweroff));
+
+	return NOTIFY_DONE;
+}
+
+static int micon_probe(struct platform_device *pdev)
+{
+	struct micon_platform_data *pdata = pdev->dev.platform_data;
+	struct micon_priv *priv;
+	struct resource *r;
+	int ret;
+
+	if (!pdata)
+		return -ENODEV;
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->dev = &pdev->dev;
+	r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+
+	/* Don't request exclusive access since 8250 may also utilize this
+	 * resource
+	 */
+	priv->base = devm_ioremap(&pdev->dev, r->start, resource_size(r));
+	if (IS_ERR(priv->base))
+		return -ENOMEM;
+
+	priv->tclk = pdata->tclk;
+
+	priv->nb.notifier_call = restart_handler;
+
+	return register_reboot_notifier(&priv->nb);
+}
+
+static struct platform_driver micon_driver = {
+	.probe	= micon_probe,
+	.driver = {
+		.name = MICON_NAME,
+	},
+};
+builtin_platform_driver(micon_driver);
diff --git a/include/linux/platform_data/micon.h b/include/linux/platform_data/micon.h
new file mode 100644
index 000000000000..67dbaad5dfaa
--- /dev/null
+++ b/include/linux/platform_data/micon.h
@@ -0,0 +1,10 @@
+#ifndef __MICON_PDATA_H
+#define __MICON_PDATA_H
+
+#define MICON_NAME	"micon"
+
+struct micon_platform_data {
+	int tclk;
+};
+
+#endif /* __MICON_PDATA_H */
-- 
2.9.3

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