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/delay.h> 15 #include <linux/device.h> 16 #include <linux/err.h> 17 #include <linux/io.h> 18 #include <linux/of.h> 19 #include <linux/platform_device.h> 20 #include <linux/reset-controller.h> 21 #include <linux/reset/reset-simple.h> 22 #include <linux/spinlock.h> 23 24 static inline struct reset_simple_data * 25 to_reset_simple_data(struct reset_controller_dev *rcdev) 26 { 27 return container_of(rcdev, struct reset_simple_data, rcdev); 28 } 29 30 static int reset_simple_update(struct reset_controller_dev *rcdev, 31 unsigned long id, bool assert) 32 { 33 struct reset_simple_data *data = to_reset_simple_data(rcdev); 34 int reg_width = sizeof(u32); 35 int bank = id / (reg_width * BITS_PER_BYTE); 36 int offset = id % (reg_width * BITS_PER_BYTE); 37 unsigned long flags; 38 u32 reg; 39 40 spin_lock_irqsave(&data->lock, flags); 41 42 reg = readl(data->membase + (bank * reg_width)); 43 if (assert ^ data->active_low) 44 reg |= BIT(offset); 45 else 46 reg &= ~BIT(offset); 47 writel(reg, data->membase + (bank * reg_width)); 48 49 spin_unlock_irqrestore(&data->lock, flags); 50 51 return 0; 52 } 53 54 static int reset_simple_assert(struct reset_controller_dev *rcdev, 55 unsigned long id) 56 { 57 return reset_simple_update(rcdev, id, true); 58 } 59 60 static int reset_simple_deassert(struct reset_controller_dev *rcdev, 61 unsigned long id) 62 { 63 return reset_simple_update(rcdev, id, false); 64 } 65 66 static int reset_simple_reset(struct reset_controller_dev *rcdev, 67 unsigned long id) 68 { 69 struct reset_simple_data *data = to_reset_simple_data(rcdev); 70 int ret; 71 72 if (!data->reset_us) 73 return -ENOTSUPP; 74 75 ret = reset_simple_assert(rcdev, id); 76 if (ret) 77 return ret; 78 79 usleep_range(data->reset_us, data->reset_us * 2); 80 81 return reset_simple_deassert(rcdev, id); 82 } 83 84 static int reset_simple_status(struct reset_controller_dev *rcdev, 85 unsigned long id) 86 { 87 struct reset_simple_data *data = to_reset_simple_data(rcdev); 88 int reg_width = sizeof(u32); 89 int bank = id / (reg_width * BITS_PER_BYTE); 90 int offset = id % (reg_width * BITS_PER_BYTE); 91 u32 reg; 92 93 reg = readl(data->membase + (bank * reg_width)); 94 95 return !(reg & BIT(offset)) ^ !data->status_active_low; 96 } 97 98 const struct reset_control_ops reset_simple_ops = { 99 .assert = reset_simple_assert, 100 .deassert = reset_simple_deassert, 101 .reset = reset_simple_reset, 102 .status = reset_simple_status, 103 }; 104 EXPORT_SYMBOL_GPL(reset_simple_ops); 105 106 /** 107 * struct reset_simple_devdata - simple reset controller properties 108 * @reg_offset: offset between base address and first reset register. 109 * @nr_resets: number of resets. If not set, default to resource size in bits. 110 * @active_low: if true, bits are cleared to assert the reset. Otherwise, bits 111 * are set to assert the reset. 112 * @status_active_low: if true, bits read back as cleared while the reset is 113 * asserted. Otherwise, bits read back as set while the 114 * reset is asserted. 115 */ 116 struct reset_simple_devdata { 117 u32 reg_offset; 118 u32 nr_resets; 119 bool active_low; 120 bool status_active_low; 121 }; 122 123 #define SOCFPGA_NR_BANKS 8 124 125 static const struct reset_simple_devdata reset_simple_socfpga = { 126 .reg_offset = 0x20, 127 .nr_resets = SOCFPGA_NR_BANKS * 32, 128 .status_active_low = true, 129 }; 130 131 static const struct reset_simple_devdata reset_simple_active_low = { 132 .active_low = true, 133 .status_active_low = true, 134 }; 135 136 static const struct of_device_id reset_simple_dt_ids[] = { 137 { .compatible = "altr,stratix10-rst-mgr", 138 .data = &reset_simple_socfpga }, 139 { .compatible = "st,stm32-rcc", }, 140 { .compatible = "allwinner,sun6i-a31-clock-reset", 141 .data = &reset_simple_active_low }, 142 { .compatible = "zte,zx296718-reset", 143 .data = &reset_simple_active_low }, 144 { .compatible = "aspeed,ast2400-lpc-reset" }, 145 { .compatible = "aspeed,ast2500-lpc-reset" }, 146 { .compatible = "aspeed,ast2600-lpc-reset" }, 147 { .compatible = "bitmain,bm1880-reset", 148 .data = &reset_simple_active_low }, 149 { .compatible = "brcm,bcm4908-misc-pcie-reset", 150 .data = &reset_simple_active_low }, 151 { .compatible = "snps,dw-high-reset" }, 152 { .compatible = "snps,dw-low-reset", 153 .data = &reset_simple_active_low }, 154 { /* sentinel */ }, 155 }; 156 157 static int reset_simple_probe(struct platform_device *pdev) 158 { 159 struct device *dev = &pdev->dev; 160 const struct reset_simple_devdata *devdata; 161 struct reset_simple_data *data; 162 void __iomem *membase; 163 struct resource *res; 164 u32 reg_offset = 0; 165 166 devdata = of_device_get_match_data(dev); 167 168 data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL); 169 if (!data) 170 return -ENOMEM; 171 172 membase = devm_platform_get_and_ioremap_resource(pdev, 0, &res); 173 if (IS_ERR(membase)) 174 return PTR_ERR(membase); 175 176 spin_lock_init(&data->lock); 177 data->membase = membase; 178 data->rcdev.owner = THIS_MODULE; 179 data->rcdev.nr_resets = resource_size(res) * BITS_PER_BYTE; 180 data->rcdev.ops = &reset_simple_ops; 181 data->rcdev.of_node = dev->of_node; 182 183 if (devdata) { 184 reg_offset = devdata->reg_offset; 185 if (devdata->nr_resets) 186 data->rcdev.nr_resets = devdata->nr_resets; 187 data->active_low = devdata->active_low; 188 data->status_active_low = devdata->status_active_low; 189 } 190 191 data->membase += reg_offset; 192 193 return devm_reset_controller_register(dev, &data->rcdev); 194 } 195 196 static struct platform_driver reset_simple_driver = { 197 .probe = reset_simple_probe, 198 .driver = { 199 .name = "simple-reset", 200 .of_match_table = reset_simple_dt_ids, 201 }, 202 }; 203 builtin_platform_driver(reset_simple_driver); 204