drivers/clk/stm32/reset-stm32.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) STMicroelectronics 2022 - All Rights Reserved
   4  * Author: Gabriel Fernandez <gabriel.fernandez@foss.st.com> for STMicroelectronics.
   5  */
   6
   7 #include <linux/of.h>
   8 #include <linux/platform_device.h>
   9 #include <linux/regmap.h>
  10 #include <linux/reset-controller.h>
  11 #include <linux/slab.h>
  12 #include <linux/spinlock.h>
  13
  14 #include "clk-stm32-core.h"
  15
  16 #define STM32_RESET_ID_MASK GENMASK(15, 0)
  17
  18 struct stm32_reset_data {
  19         /* reset lock */
  20         spinlock_t                      lock;
  21         struct reset_controller_dev     rcdev;
  22         void __iomem                    *membase;
  23         u32                             clear_offset;
  24 };
  25
  26 static inline struct stm32_reset_data *
  27 to_stm32_reset_data(struct reset_controller_dev *rcdev)
  28 {
  29         return container_of(rcdev, struct stm32_reset_data, rcdev);
  30 }
  31
  32 static int stm32_reset_update(struct reset_controller_dev *rcdev,
  33                               unsigned long id, bool assert)
  34 {
  35         struct stm32_reset_data *data = to_stm32_reset_data(rcdev);
  36         int reg_width = sizeof(u32);
  37         int bank = id / (reg_width * BITS_PER_BYTE);
  38         int offset = id % (reg_width * BITS_PER_BYTE);
  39
  40         if (data->clear_offset) {
  41                 void __iomem *addr;
  42
  43                 addr = data->membase + (bank * reg_width);
  44                 if (!assert)
  45                         addr += data->clear_offset;
  46
  47                 writel(BIT(offset), addr);
  48
  49         } else {
  50                 unsigned long flags;
  51                 u32 reg;
  52
  53                 spin_lock_irqsave(&data->lock, flags);
  54
  55                 reg = readl(data->membase + (bank * reg_width));
  56
  57                 if (assert)
  58                         reg |= BIT(offset);
  59                 else
  60                         reg &= ~BIT(offset);
  61
  62                 writel(reg, data->membase + (bank * reg_width));
  63
  64                 spin_unlock_irqrestore(&data->lock, flags);
  65         }
  66
  67         return 0;
  68 }
  69
  70 static int stm32_reset_assert(struct reset_controller_dev *rcdev,
  71                               unsigned long id)
  72 {
  73         return stm32_reset_update(rcdev, id, true);
  74 }
  75
  76 static int stm32_reset_deassert(struct reset_controller_dev *rcdev,
  77                                 unsigned long id)
  78 {
  79         return stm32_reset_update(rcdev, id, false);
  80 }
  81
  82 static int stm32_reset_status(struct reset_controller_dev *rcdev,
  83                               unsigned long id)
  84 {
  85         struct stm32_reset_data *data = to_stm32_reset_data(rcdev);
  86         int reg_width = sizeof(u32);
  87         int bank = id / (reg_width * BITS_PER_BYTE);
  88         int offset = id % (reg_width * BITS_PER_BYTE);
  89         u32 reg;
  90
  91         reg = readl(data->membase + (bank * reg_width));
  92
  93         return !!(reg & BIT(offset));
  94 }
  95
  96 static const struct reset_control_ops stm32_reset_ops = {
  97         .assert         = stm32_reset_assert,
  98         .deassert       = stm32_reset_deassert,
  99         .status         = stm32_reset_status,
 100 };
 101
 102 int stm32_rcc_reset_init(struct device *dev, const struct of_device_id *match,
 103                          void __iomem *base)
 104 {
 105         const struct stm32_rcc_match_data *data = match->data;
 106         struct stm32_reset_data *reset_data = NULL;
 107
 108         data = match->data;
 109
 110         reset_data = kzalloc(sizeof(*reset_data), GFP_KERNEL);
 111         if (!reset_data)
 112                 return -ENOMEM;
 113
 114         reset_data->membase = base;
 115         reset_data->rcdev.owner = THIS_MODULE;
 116         reset_data->rcdev.ops = &stm32_reset_ops;
 117         reset_data->rcdev.of_node = dev_of_node(dev);
 118         reset_data->rcdev.nr_resets = STM32_RESET_ID_MASK;
 119         reset_data->clear_offset = data->clear_offset;
 120
 121         return reset_controller_register(&reset_data->rcdev);
 122 }