drivers/reset/reset-simple.c

   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         { .compatible = "snps,dw-high-reset" },
 131         { .compatible = "snps,dw-low-reset",
 132                 .data = &reset_simple_active_low },
 133         { /* sentinel */ },
 134 };
 135
 136 static int reset_simple_probe(struct platform_device *pdev)
 137 {
 138         struct device *dev = &pdev->dev;
 139         const struct reset_simple_devdata *devdata;
 140         struct reset_simple_data *data;
 141         void __iomem *membase;
 142         struct resource *res;
 143         u32 reg_offset = 0;
 144
 145         devdata = of_device_get_match_data(dev);
 146
 147         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 148         if (!data)
 149                 return -ENOMEM;
 150
 151         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 152         membase = devm_ioremap_resource(dev, res);
 153         if (IS_ERR(membase))
 154                 return PTR_ERR(membase);
 155
 156         spin_lock_init(&data->lock);
 157         data->membase = membase;
 158         data->rcdev.owner = THIS_MODULE;
 159         data->rcdev.nr_resets = resource_size(res) * BITS_PER_BYTE;
 160         data->rcdev.ops = &reset_simple_ops;
 161         data->rcdev.of_node = dev->of_node;
 162
 163         if (devdata) {
 164                 reg_offset = devdata->reg_offset;
 165                 if (devdata->nr_resets)
 166                         data->rcdev.nr_resets = devdata->nr_resets;
 167                 data->active_low = devdata->active_low;
 168                 data->status_active_low = devdata->status_active_low;
 169         }
 170
 171         data->membase += reg_offset;
 172
 173         return devm_reset_controller_register(dev, &data->rcdev);
 174 }
 175
 176 static struct platform_driver reset_simple_driver = {
 177         .probe  = reset_simple_probe,
 178         .driver = {
 179                 .name           = "simple-reset",
 180                 .of_match_table = reset_simple_dt_ids,
 181         },
 182 };
 183 builtin_platform_driver(reset_simple_driver);