1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Generic Syscon Poweroff Driver 4 * 5 * Copyright (c) 2015, National Instruments Corp. 6 * Author: Moritz Fischer <moritz.fischer@ettus.com> 7 */ 8 9 #include <linux/delay.h> 10 #include <linux/io.h> 11 #include <linux/notifier.h> 12 #include <linux/mfd/syscon.h> 13 #include <linux/of_address.h> 14 #include <linux/of_device.h> 15 #include <linux/platform_device.h> 16 #include <linux/pm.h> 17 #include <linux/regmap.h> 18 19 static struct regmap *map; 20 static u32 offset; 21 static u32 value; 22 static u32 mask; 23 24 static void syscon_poweroff(void) 25 { 26 /* Issue the poweroff */ 27 regmap_update_bits(map, offset, mask, value); 28 29 mdelay(1000); 30 31 pr_emerg("Unable to poweroff system\n"); 32 } 33 34 static int syscon_poweroff_probe(struct platform_device *pdev) 35 { 36 int mask_err, value_err; 37 38 map = syscon_regmap_lookup_by_phandle(pdev->dev.of_node, "regmap"); 39 if (IS_ERR(map)) { 40 dev_err(&pdev->dev, "unable to get syscon"); 41 return PTR_ERR(map); 42 } 43 44 if (of_property_read_u32(pdev->dev.of_node, "offset", &offset)) { 45 dev_err(&pdev->dev, "unable to read 'offset'"); 46 return -EINVAL; 47 } 48 49 value_err = of_property_read_u32(pdev->dev.of_node, "value", &value); 50 mask_err = of_property_read_u32(pdev->dev.of_node, "mask", &mask); 51 if (value_err && mask_err) { 52 dev_err(&pdev->dev, "unable to read 'value' and 'mask'"); 53 return -EINVAL; 54 } 55 56 if (value_err) { 57 /* support old binding */ 58 value = mask; 59 mask = 0xFFFFFFFF; 60 } else if (mask_err) { 61 /* support value without mask*/ 62 mask = 0xFFFFFFFF; 63 } 64 65 if (pm_power_off) { 66 dev_err(&pdev->dev, "pm_power_off already claimed for %ps", 67 pm_power_off); 68 return -EBUSY; 69 } 70 71 pm_power_off = syscon_poweroff; 72 73 return 0; 74 } 75 76 static int syscon_poweroff_remove(struct platform_device *pdev) 77 { 78 if (pm_power_off == syscon_poweroff) 79 pm_power_off = NULL; 80 81 return 0; 82 } 83 84 static const struct of_device_id syscon_poweroff_of_match[] = { 85 { .compatible = "syscon-poweroff" }, 86 {} 87 }; 88 89 static struct platform_driver syscon_poweroff_driver = { 90 .probe = syscon_poweroff_probe, 91 .remove = syscon_poweroff_remove, 92 .driver = { 93 .name = "syscon-poweroff", 94 .of_match_table = syscon_poweroff_of_match, 95 }, 96 }; 97 98 static int __init syscon_poweroff_register(void) 99 { 100 return platform_driver_register(&syscon_poweroff_driver); 101 } 102 device_initcall(syscon_poweroff_register); 103