1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Cirrus EP93xx SoC reset driver 4 * 5 * Copyright (C) 2021 Nikita Shubin <nikita.shubin@maquefel.me> 6 */ 7 8 #include <linux/bits.h> 9 #include <linux/container_of.h> 10 #include <linux/delay.h> 11 #include <linux/errno.h> 12 #include <linux/mfd/syscon.h> 13 #include <linux/module.h> 14 #include <linux/mod_devicetable.h> 15 #include <linux/notifier.h> 16 #include <linux/reboot.h> 17 #include <linux/slab.h> 18 19 #include <linux/soc/cirrus/ep93xx.h> 20 21 #define EP93XX_SYSCON_DEVCFG 0x80 22 #define EP93XX_SYSCON_DEVCFG_SWRST BIT(31) 23 24 struct ep93xx_restart { 25 struct ep93xx_regmap_adev *aux_dev; 26 struct notifier_block restart_handler; 27 }; 28 29 static int ep93xx_restart_handle(struct notifier_block *this, 30 unsigned long mode, void *cmd) 31 { 32 struct ep93xx_restart *priv = 33 container_of(this, struct ep93xx_restart, restart_handler); 34 struct ep93xx_regmap_adev *aux = priv->aux_dev; 35 36 /* Issue the reboot */ 37 aux->update_bits(aux->map, aux->lock, EP93XX_SYSCON_DEVCFG, 38 EP93XX_SYSCON_DEVCFG_SWRST, EP93XX_SYSCON_DEVCFG_SWRST); 39 aux->update_bits(aux->map, aux->lock, EP93XX_SYSCON_DEVCFG, 40 EP93XX_SYSCON_DEVCFG_SWRST, 0); 41 42 return NOTIFY_DONE; 43 } 44 45 static int ep93xx_reboot_probe(struct auxiliary_device *adev, 46 const struct auxiliary_device_id *id) 47 { 48 struct ep93xx_regmap_adev *rdev = to_ep93xx_regmap_adev(adev); 49 struct device *dev = &adev->dev; 50 struct ep93xx_restart *priv; 51 int err; 52 53 if (!rdev->update_bits) 54 return -ENODEV; 55 56 priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL); 57 if (!priv) 58 return -ENOMEM; 59 60 priv->aux_dev = rdev; 61 62 priv->restart_handler.notifier_call = ep93xx_restart_handle; 63 priv->restart_handler.priority = 128; 64 65 err = register_restart_handler(&priv->restart_handler); 66 if (err) 67 return dev_err_probe(dev, err, "can't register restart notifier\n"); 68 69 return 0; 70 } 71 72 static const struct auxiliary_device_id ep93xx_reboot_ids[] = { 73 { 74 .name = "soc_ep93xx.reset-ep93xx", 75 }, 76 { /* sentinel */ } 77 }; 78 MODULE_DEVICE_TABLE(auxiliary, ep93xx_reboot_ids); 79 80 static struct auxiliary_driver ep93xx_reboot_driver = { 81 .probe = ep93xx_reboot_probe, 82 .id_table = ep93xx_reboot_ids, 83 }; 84 module_auxiliary_driver(ep93xx_reboot_driver); 85