dm: reset: add stm32 reset driver

This driver is adapted from linux drivers/reset/reset-stm32.c
It's compatible with STM32 F4/F7/H7 SoCs.

This driver doesn't implement .of_match as it's binded
by MFD RCC driver.

To add support for each SoC family, a SoC's specific
include/dt-binfings/mfd/stm32xx-rcc.h file must be added.

This patch only includes stm32h7-rcc.h dedicated for STM32H7 SoCs.
Other SoCs support will be added in the future.

Signed-off-by: Patrice Chotard <patrice.chotard@st.com>
Reviewed-by: Simon Glass <sjg@chromium.org>

3 files changed, 88 insertions, 0 deletions

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index e6af7da..ce46e27 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -28,6 +28,13 @@ config STI_RESET
 	  Say Y if you want to control reset signals provided by system config
 	  block.
 
+config STM32_RESET
+	bool "Enable the STM32 reset"
+	depends on STM32
+	help
+	  Support for reset controllers on STMicroelectronics STM32 family SoCs.
+	  This resset driver is compatible with STM32 F4/F7 and H7 SoCs.
+
 config TEGRA_CAR_RESET
 	bool "Enable Tegra CAR-based reset driver"
 	depends on TEGRA_CAR
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index d5e06c2..252cefe 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -6,6 +6,7 @@ obj-$(CONFIG_DM_RESET) += reset-uclass.o
 obj-$(CONFIG_SANDBOX_MBOX) += sandbox-reset.o
 obj-$(CONFIG_SANDBOX_MBOX) += sandbox-reset-test.o
 obj-$(CONFIG_STI_RESET) += sti-reset.o
+obj-$(CONFIG_STM32_RESET) += stm32-reset.o
 obj-$(CONFIG_TEGRA_CAR_RESET) += tegra-car-reset.o
 obj-$(CONFIG_TEGRA186_RESET) += tegra186-reset.o
 obj-$(CONFIG_RESET_BCM6345) += reset-bcm6345.o
diff --git a/drivers/reset/stm32-reset.c b/drivers/reset/stm32-reset.c
new file mode 100644
index 0000000..9c627d8
--- /dev/null
+++ b/drivers/reset/stm32-reset.c
@@ -0,0 +1,80 @@
+/*
+ * Copyright (C) STMicroelectronics SA 2017
+ * Author(s): Patrice CHOTARD, <patrice.chotard@st.com> for STMicroelectronics.
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <errno.h>
+#include <reset-uclass.h>
+#include <asm/io.h>
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct stm32_reset_priv {
+	fdt_addr_t base;
+};
+
+static int stm32_reset_request(struct reset_ctl *reset_ctl)
+{
+	return 0;
+}
+
+static int stm32_reset_free(struct reset_ctl *reset_ctl)
+{
+	return 0;
+}
+
+static int stm32_reset_assert(struct reset_ctl *reset_ctl)
+{
+	struct stm32_reset_priv *priv = dev_get_priv(reset_ctl->dev);
+	int bank = (reset_ctl->id / BITS_PER_LONG) * 4;
+	int offset = reset_ctl->id % BITS_PER_LONG;
+	debug("%s: reset id = %ld bank = %d offset = %d)\n", __func__,
+	      reset_ctl->id, bank, offset);
+
+	setbits_le32(priv->base + bank, BIT(offset));
+
+	return 0;
+}
+
+static int stm32_reset_deassert(struct reset_ctl *reset_ctl)
+{
+	struct stm32_reset_priv *priv = dev_get_priv(reset_ctl->dev);
+	int bank = (reset_ctl->id / BITS_PER_LONG) * 4;
+	int offset = reset_ctl->id % BITS_PER_LONG;
+	debug("%s: reset id = %ld bank = %d offset = %d)\n", __func__,
+	      reset_ctl->id, bank, offset);
+
+	clrbits_le32(priv->base + bank, BIT(offset));
+
+	return 0;
+}
+
+static const struct reset_ops stm32_reset_ops = {
+	.request	= stm32_reset_request,
+	.free		= stm32_reset_free,
+	.rst_assert	= stm32_reset_assert,
+	.rst_deassert	= stm32_reset_deassert,
+};
+
+static int stm32_reset_probe(struct udevice *dev)
+{
+	struct stm32_reset_priv *priv = dev_get_priv(dev);
+
+	priv->base = devfdt_get_addr(dev);
+	if (priv->base == FDT_ADDR_T_NONE)
+		return -EINVAL;
+
+	return 0;
+}
+
+U_BOOT_DRIVER(stm32_rcc_reset) = {
+	.name			= "stm32_rcc_reset",
+	.id			= UCLASS_RESET,
+	.probe			= stm32_reset_probe,
+	.priv_auto_alloc_size	= sizeof(struct stm32_reset_priv),
+	.ops			= &stm32_reset_ops,
+};