1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * Simple Reset Controller Driver 4 * 5 * Copyright (C) 2017 Pengutronix, Philipp Zabel <kernel@pengutronix.de> 6 * 7 * Based on Allwinner SoCs Reset Controller driver 8 * 9 * Copyright 2013 Maxime Ripard 10 * 11 * Maxime Ripard <maxime.ripard@free-electrons.com> 12 */ 13 14 #include <linux/device.h> 15 #include <linux/err.h> 16 #include <linux/io.h> 17 #include <linux/of.h> 18 #include <linux/of_device.h> 19 #include <linux/platform_device.h> 20 #include <linux/reset-controller.h> 21 #include <linux/spinlock.h> 22 23 #include "reset-simple.h" 24 25 static inline struct reset_simple_data * 26 to_reset_simple_data(struct reset_controller_dev *rcdev) 27 { 28 return container_of(rcdev, struct reset_simple_data, rcdev); 29 } 30 31 static int reset_simple_update(struct reset_controller_dev *rcdev, 32 unsigned long id, bool assert) 33 { 34 struct reset_simple_data *data = to_reset_simple_data(rcdev); 35 int reg_width = sizeof(u32); 36 int bank = id / (reg_width * BITS_PER_BYTE); 37 int offset = id % (reg_width * BITS_PER_BYTE); 38 unsigned long flags; 39 u32 reg; 40 41 spin_lock_irqsave(&data->lock, flags); 42 43 reg = readl(data->membase + (bank * reg_width)); 44 if (assert ^ data->active_low) 45 reg |= BIT(offset); 46 else 47 reg &= ~BIT(offset); 48 writel(reg, data->membase + (bank * reg_width)); 49 50 spin_unlock_irqrestore(&data->lock, flags); 51 52 return 0; 53 } 54 55 static int reset_simple_assert(struct reset_controller_dev *rcdev, 56 unsigned long id) 57 { 58 return reset_simple_update(rcdev, id, true); 59 } 60 61 static int reset_simple_deassert(struct reset_controller_dev *rcdev, 62 unsigned long id) 63 { 64 return reset_simple_update(rcdev, id, false); 65 } 66 67 static int reset_simple_status(struct reset_controller_dev *rcdev, 68 unsigned long id) 69 { 70 struct reset_simple_data *data = to_reset_simple_data(rcdev); 71 int reg_width = sizeof(u32); 72 int bank = id / (reg_width * BITS_PER_BYTE); 73 int offset = id % (reg_width * BITS_PER_BYTE); 74 u32 reg; 75 76 reg = readl(data->membase + (bank * reg_width)); 77 78 return !(reg & BIT(offset)) ^ !data->status_active_low; 79 } 80 81 const struct reset_control_ops reset_simple_ops = { 82 .assert = reset_simple_assert, 83 .deassert = reset_simple_deassert, 84 .status = reset_simple_status, 85 }; 86 EXPORT_SYMBOL_GPL(reset_simple_ops); 87 88 /** 89 * struct reset_simple_devdata - simple reset controller properties 90 * @reg_offset: offset between base address and first reset register. 91 * @nr_resets: number of resets. If not set, default to resource size in bits. 92 * @active_low: if true, bits are cleared to assert the reset. Otherwise, bits 93 * are set to assert the reset. 94 * @status_active_low: if true, bits read back as cleared while the reset is 95 * asserted. Otherwise, bits read back as set while the 96 * reset is asserted. 97 */ 98 struct reset_simple_devdata { 99 u32 reg_offset; 100 u32 nr_resets; 101 bool active_low; 102 bool status_active_low; 103 }; 104 105 #define SOCFPGA_NR_BANKS 8 106 107 static const struct reset_simple_devdata reset_simple_socfpga = { 108 .reg_offset = 0x20, 109 .nr_resets = SOCFPGA_NR_BANKS * 32, 110 .status_active_low = true, 111 }; 112 113 static const struct reset_simple_devdata reset_simple_active_low = { 114 .active_low = true, 115 .status_active_low = true, 116 }; 117 118 static const struct of_device_id reset_simple_dt_ids[] = { 119 { .compatible = "altr,stratix10-rst-mgr", 120 .data = &reset_simple_socfpga }, 121 { .compatible = "st,stm32-rcc", }, 122 { .compatible = "allwinner,sun6i-a31-clock-reset", 123 .data = &reset_simple_active_low }, 124 { .compatible = "zte,zx296718-reset", 125 .data = &reset_simple_active_low }, 126 { .compatible = "aspeed,ast2400-lpc-reset" }, 127 { .compatible = "aspeed,ast2500-lpc-reset" }, 128 { .compatible = "bitmain,bm1880-reset", 129 .data = &reset_simple_active_low }, 130 { /* sentinel */ }, 131 }; 132 133 static int reset_simple_probe(struct platform_device *pdev) 134 { 135 struct device *dev = &pdev->dev; 136 const struct reset_simple_devdata *devdata; 137 struct reset_simple_data *data; 138 void __iomem *membase; 139 struct resource *res; 140 u32 reg_offset = 0; 141 142 devdata = of_device_get_match_data(dev); 143 144 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); 145 if (!data) 146 return -ENOMEM; 147 148 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 149 membase = devm_ioremap_resource(dev, res); 150 if (IS_ERR(membase)) 151 return PTR_ERR(membase); 152 153 spin_lock_init(&data->lock); 154 data->membase = membase; 155 data->rcdev.owner = THIS_MODULE; 156 data->rcdev.nr_resets = resource_size(res) * BITS_PER_BYTE; 157 data->rcdev.ops = &reset_simple_ops; 158 data->rcdev.of_node = dev->of_node; 159 160 if (devdata) { 161 reg_offset = devdata->reg_offset; 162 if (devdata->nr_resets) 163 data->rcdev.nr_resets = devdata->nr_resets; 164 data->active_low = devdata->active_low; 165 data->status_active_low = devdata->status_active_low; 166 } 167 168 data->membase += reg_offset; 169 170 return devm_reset_controller_register(dev, &data->rcdev); 171 } 172 173 static struct platform_driver reset_simple_driver = { 174 .probe = reset_simple_probe, 175 .driver = { 176 .name = "simple-reset", 177 .of_match_table = reset_simple_dt_ids, 178 }, 179 }; 180 builtin_platform_driver(reset_simple_driver); 181