drivers/reset/reset-stm32mp1.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) STMicroelectronics 2018 - All Rights Reserved
   4  * Author: Gabriel Fernandez <gabriel.fernandez@st.com> for STMicroelectronics.
   5  */
   6
   7 #include <linux/device.h>
   8 #include <linux/err.h>
   9 #include <linux/io.h>
  10 #include <linux/of.h>
  11 #include <linux/platform_device.h>
  12 #include <linux/reset-controller.h>
  13
  14 #define CLR_OFFSET 0x4
  15
  16 struct stm32_reset_data {
  17         struct reset_controller_dev     rcdev;
  18         void __iomem                    *membase;
  19 };
  20
  21 static inline struct stm32_reset_data *
  22 to_stm32_reset_data(struct reset_controller_dev *rcdev)
  23 {
  24         return container_of(rcdev, struct stm32_reset_data, rcdev);
  25 }
  26
  27 static int stm32_reset_update(struct reset_controller_dev *rcdev,
  28                               unsigned long id, bool assert)
  29 {
  30         struct stm32_reset_data *data = to_stm32_reset_data(rcdev);
  31         int reg_width = sizeof(u32);
  32         int bank = id / (reg_width * BITS_PER_BYTE);
  33         int offset = id % (reg_width * BITS_PER_BYTE);
  34         void __iomem *addr;
  35
  36         addr = data->membase + (bank * reg_width);
  37         if (!assert)
  38                 addr += CLR_OFFSET;
  39
  40         writel(BIT(offset), addr);
  41
  42         return 0;
  43 }
  44
  45 static int stm32_reset_assert(struct reset_controller_dev *rcdev,
  46                               unsigned long id)
  47 {
  48         return stm32_reset_update(rcdev, id, true);
  49 }
  50
  51 static int stm32_reset_deassert(struct reset_controller_dev *rcdev,
  52                                 unsigned long id)
  53 {
  54         return stm32_reset_update(rcdev, id, false);
  55 }
  56
  57 static int stm32_reset_status(struct reset_controller_dev *rcdev,
  58                               unsigned long id)
  59 {
  60         struct stm32_reset_data *data = to_stm32_reset_data(rcdev);
  61         int reg_width = sizeof(u32);
  62         int bank = id / (reg_width * BITS_PER_BYTE);
  63         int offset = id % (reg_width * BITS_PER_BYTE);
  64         u32 reg;
  65
  66         reg = readl(data->membase + (bank * reg_width));
  67
  68         return !!(reg & BIT(offset));
  69 }
  70
  71 static const struct reset_control_ops stm32_reset_ops = {
  72         .assert         = stm32_reset_assert,
  73         .deassert       = stm32_reset_deassert,
  74         .status         = stm32_reset_status,
  75 };
  76
  77 static const struct of_device_id stm32_reset_dt_ids[] = {
  78         { .compatible = "st,stm32mp1-rcc"},
  79         { /* sentinel */ },
  80 };
  81
  82 static int stm32_reset_probe(struct platform_device *pdev)
  83 {
  84         struct device *dev = &pdev->dev;
  85         struct stm32_reset_data *data;
  86         void __iomem *membase;
  87         struct resource *res;
  88
  89         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
  90         if (!data)
  91                 return -ENOMEM;
  92
  93         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  94         membase = devm_ioremap_resource(dev, res);
  95         if (IS_ERR(membase))
  96                 return PTR_ERR(membase);
  97
  98         data->membase = membase;
  99         data->rcdev.owner = THIS_MODULE;
 100         data->rcdev.nr_resets = resource_size(res) * BITS_PER_BYTE;
 101         data->rcdev.ops = &stm32_reset_ops;
 102         data->rcdev.of_node = dev->of_node;
 103
 104         return devm_reset_controller_register(dev, &data->rcdev);
 105 }
 106
 107 static struct platform_driver stm32_reset_driver = {
 108         .probe  = stm32_reset_probe,
 109         .driver = {
 110                 .name           = "stm32mp1-reset",
 111                 .of_match_table = stm32_reset_dt_ids,
 112         },
 113 };
 114
 115 builtin_platform_driver(stm32_reset_driver);