1 /* 2 * QNAP Turbo NAS Board power off 3 * 4 * Copyright (C) 2012 Andrew Lunn <andrew@lunn.ch> 5 * 6 * Based on the code from: 7 * 8 * Copyright (C) 2009 Martin Michlmayr <tbm@cyrius.com> 9 * Copyright (C) 2008 Byron Bradley <byron.bbradley@gmail.com> 10 * 11 * This program is free software; you can redistribute it and/or 12 * modify it under the terms of the GNU General Public License 13 * as published by the Free Software Foundation; either version 14 * 2 of the License, or (at your option) any later version. 15 */ 16 17 #include <linux/kernel.h> 18 #include <linux/module.h> 19 #include <linux/platform_device.h> 20 #include <linux/serial_reg.h> 21 #include <linux/kallsyms.h> 22 #include <linux/of.h> 23 #include <linux/io.h> 24 #include <linux/clk.h> 25 26 #define UART1_REG(x) (base + ((UART_##x) << 2)) 27 28 static void __iomem *base; 29 static unsigned long tclk; 30 31 static void qnap_power_off(void) 32 { 33 /* 19200 baud divisor */ 34 const unsigned divisor = ((tclk + (8 * 19200)) / (16 * 19200)); 35 36 pr_err("%s: triggering power-off...\n", __func__); 37 38 /* hijack UART1 and reset into sane state (19200,8n1) */ 39 writel(0x83, UART1_REG(LCR)); 40 writel(divisor & 0xff, UART1_REG(DLL)); 41 writel((divisor >> 8) & 0xff, UART1_REG(DLM)); 42 writel(0x03, UART1_REG(LCR)); 43 writel(0x00, UART1_REG(IER)); 44 writel(0x00, UART1_REG(FCR)); 45 writel(0x00, UART1_REG(MCR)); 46 47 /* send the power-off command 'A' to PIC */ 48 writel('A', UART1_REG(TX)); 49 } 50 51 static int qnap_power_off_probe(struct platform_device *pdev) 52 { 53 struct resource *res; 54 struct clk *clk; 55 char symname[KSYM_NAME_LEN]; 56 57 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 58 if (!res) { 59 dev_err(&pdev->dev, "Missing resource"); 60 return -EINVAL; 61 } 62 63 base = devm_ioremap(&pdev->dev, res->start, resource_size(res)); 64 if (!base) { 65 dev_err(&pdev->dev, "Unable to map resource"); 66 return -EINVAL; 67 } 68 69 /* We need to know tclk in order to calculate the UART divisor */ 70 clk = devm_clk_get(&pdev->dev, NULL); 71 if (IS_ERR(clk)) { 72 dev_err(&pdev->dev, "Clk missing"); 73 return PTR_ERR(clk); 74 } 75 76 tclk = clk_get_rate(clk); 77 78 /* Check that nothing else has already setup a handler */ 79 if (pm_power_off) { 80 lookup_symbol_name((ulong)pm_power_off, symname); 81 dev_err(&pdev->dev, 82 "pm_power_off already claimed %p %s", 83 pm_power_off, symname); 84 return -EBUSY; 85 } 86 pm_power_off = qnap_power_off; 87 88 return 0; 89 } 90 91 static int qnap_power_off_remove(struct platform_device *pdev) 92 { 93 pm_power_off = NULL; 94 return 0; 95 } 96 97 static const struct of_device_id qnap_power_off_of_match_table[] = { 98 { .compatible = "qnap,power-off", }, 99 {} 100 }; 101 MODULE_DEVICE_TABLE(of, qnap_power_off_of_match_table); 102 103 static struct platform_driver qnap_power_off_driver = { 104 .probe = qnap_power_off_probe, 105 .remove = qnap_power_off_remove, 106 .driver = { 107 .owner = THIS_MODULE, 108 .name = "qnap_power_off", 109 .of_match_table = of_match_ptr(qnap_power_off_of_match_table), 110 }, 111 }; 112 module_platform_driver(qnap_power_off_driver); 113 114 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch>"); 115 MODULE_DESCRIPTION("QNAP Power off driver"); 116 MODULE_LICENSE("GPL v2"); 117