drivers: reset: Add STM32 reset driver

[cascardo/linux.git] / drivers / reset / reset-stm32.c

diff --git a/drivers/reset/reset-stm32.c b/drivers/reset/reset-stm32.c
new file mode 100644 (file)
index 0000000..3a7c852
--- /dev/null
+++ b/drivers/reset/reset-stm32.c
@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) Maxime Coquelin 2015
+ * Author:  Maxime Coquelin <mcoquelin.stm32@gmail.com>
+ * License terms:  GNU General Public License (GPL), version 2
+ *
+ * Heavily based on sunxi driver from Maxime Ripard.
+ */
+
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+
+struct stm32_reset_data {
+       spinlock_t                      lock;
+       void __iomem                    *membase;
+       struct reset_controller_dev     rcdev;
+};
+
+static int stm32_reset_assert(struct reset_controller_dev *rcdev,
+                             unsigned long id)
+{
+       struct stm32_reset_data *data = container_of(rcdev,
+                                                    struct stm32_reset_data,
+                                                    rcdev);
+       int bank = id / BITS_PER_LONG;
+       int offset = id % BITS_PER_LONG;
+       unsigned long flags;
+       u32 reg;
+
+       spin_lock_irqsave(&data->lock, flags);
+
+       reg = readl(data->membase + (bank * 4));
+       writel(reg | BIT(offset), data->membase + (bank * 4));
+
+       spin_unlock_irqrestore(&data->lock, flags);
+
+       return 0;
+}
+
+static int stm32_reset_deassert(struct reset_controller_dev *rcdev,
+                               unsigned long id)
+{
+       struct stm32_reset_data *data = container_of(rcdev,
+                                                    struct stm32_reset_data,
+                                                    rcdev);
+       int bank = id / BITS_PER_LONG;
+       int offset = id % BITS_PER_LONG;
+       unsigned long flags;
+       u32 reg;
+
+       spin_lock_irqsave(&data->lock, flags);
+
+       reg = readl(data->membase + (bank * 4));
+       writel(reg & ~BIT(offset), data->membase + (bank * 4));
+
+       spin_unlock_irqrestore(&data->lock, flags);
+
+       return 0;
+}
+
+static const struct reset_control_ops stm32_reset_ops = {
+       .assert         = stm32_reset_assert,
+       .deassert       = stm32_reset_deassert,
+};
+
+static const struct of_device_id stm32_reset_dt_ids[] = {
+        { .compatible = "st,stm32-rcc", },
+        { /* sentinel */ },
+};
+
+static int stm32_reset_probe(struct platform_device *pdev)
+{
+       struct stm32_reset_data *data;
+       struct resource *res;
+
+       data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
+       if (!data)
+               return -ENOMEM;
+
+       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+       data->membase = devm_ioremap_resource(&pdev->dev, res);
+       if (IS_ERR(data->membase))
+               return PTR_ERR(data->membase);
+
+       spin_lock_init(&data->lock);
+
+       data->rcdev.owner = THIS_MODULE;
+       data->rcdev.nr_resets = resource_size(res) * 8;
+       data->rcdev.ops = &stm32_reset_ops;
+       data->rcdev.of_node = pdev->dev.of_node;
+
+       return devm_reset_controller_register(&pdev->dev, &data->rcdev);
+}
+
+static struct platform_driver stm32_reset_driver = {
+       .probe  = stm32_reset_probe,
+       .driver = {
+               .name           = "stm32-rcc-reset",
+               .of_match_table = stm32_reset_dt_ids,
+       },
+};
+builtin_platform_driver(stm32_reset_driver);