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