/*
* QNAP Turbo NAS Board power off
*
* Copyright (C) 2012 Andrew Lunn <andrew@lunn.ch>
*
* Based on the code from:
*
* Copyright (C) 2009 Martin Michlmayr <tbm@cyrius.com>
* Copyright (C) 2008 Byron Bradley <byron.bbradley@gmail.com>
*
* 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>
#define UART1_REG(x) (base + ((UART_##x) << 2))
static void __iomem *base;
static unsigned long tclk;
static void qnap_power_off(void)
{
/* 19200 baud divisor */
const unsigned divisor = ((tclk + (8 * 19200)) / (16 * 19200));
pr_err("%s: triggering power-off...\n", __func__);
/* hijack UART1 and reset into sane state (19200,8n1) */
writel(0x83, UART1_REG(LCR));
writel(divisor & 0xff, UART1_REG(DLL));
writel((divisor >> 8) & 0xff, UART1_REG(DLM));
writel(0x03, UART1_REG(LCR));
writel(0x00, UART1_REG(IER));
writel(0x00, UART1_REG(FCR));
writel(0x00, UART1_REG(MCR));
/* send the power-off command 'A' to PIC */
writel('A', UART1_REG(TX));
}
static int qnap_power_off_probe(struct platform_device *pdev)
{
struct resource *res;
struct clk *clk;
char symname[KSYM_NAME_LEN];
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 = qnap_power_off;
return 0;
}
static int qnap_power_off_remove(struct platform_device *pdev)
{
pm_power_off = NULL;
return 0;
}
static const struct of_device_id qnap_power_off_of_match_table[] = {
{ .compatible = "qnap,power-off", },
{}
};
MODULE_DEVICE_TABLE(of, qnap_power_off_of_match_table);
static struct platform_driver qnap_power_off_driver = {
.probe = qnap_power_off_probe,
.remove = qnap_power_off_remove,
.driver = {
.owner = THIS_MODULE,
.name = "qnap_power_off",
.of_match_table = of_match_ptr(qnap_power_off_of_match_table),
},
};
module_platform_driver(qnap_power_off_driver);
MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>");
MODULE_DESCRIPTION("QNAP Power off driver");
MODULE_LICENSE("GPL v2");
