[PATCH v2 1/4] ARM: at91: add support for SAM9 SoC reset

[Ahmad Fatoum <a.fatoum@pengutronix.de>]

System reset wasn't supported on the sama5 so far.
Add a driver to remedy this.

Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
---
v1 -> v2:
  * s/_/-/ in reset name to be consistent with driver name (Sam)
  * return restart_handler_register(...) in probe instead of separate
    return 0 after the register
  
---
 arch/arm/mach-at91/Kconfig    |  5 +++
 arch/arm/mach-at91/Makefile   |  1 +
 arch/arm/mach-at91/sam9_rst.c | 72 +++++++++++++++++++++++++++++++++++
 3 files changed, 78 insertions(+)
 create mode 100644 arch/arm/mach-at91/sam9_rst.c

diff --git a/arch/arm/mach-at91/Kconfig b/arch/arm/mach-at91/Kconfig
index 5267102bf94e..0eb5410664bb 100644
--- a/arch/arm/mach-at91/Kconfig
+++ b/arch/arm/mach-at91/Kconfig
@@ -41,12 +41,16 @@ config AT91SAM926X_BOARD_INIT
 config AT91SAM9_SMC
 	bool
 
+config HAVE_AT91SAM9_RST
+	bool
+
 config SOC_AT91SAM9
 	bool
 	select CPU_ARM926T
 	select AT91SAM9_SMC
 	select CLOCKSOURCE_ATMEL_PIT
 	select PINCTRL
+	select HAVE_AT91SAM9_RST
 	select HAVE_AT91_SMD
 	select HAVE_AT91_USB_CLK
 	select HAVE_AT91_UTMI
@@ -54,6 +58,7 @@ config SOC_AT91SAM9
 
 config SOC_SAMA5
 	bool
+	select HAVE_AT91SAM9_RST
 	select CPU_V7
 
 config SOC_SAMA5D2
diff --git a/arch/arm/mach-at91/Makefile b/arch/arm/mach-at91/Makefile
index 66d0b700f61e..89aff54b8af7 100644
--- a/arch/arm/mach-at91/Makefile
+++ b/arch/arm/mach-at91/Makefile
@@ -13,6 +13,7 @@ obj-y += at91sam9_reset.o
 obj-y += at91sam9g45_reset.o
 
 obj-$(CONFIG_AT91SAM9_SMC) += sam9_smc.o
+obj-$(CONFIG_HAVE_AT91SAM9_RST) += at91sam9_rst.o
 
 # CPU-specific support
 obj-$(CONFIG_SOC_AT91RM9200)	+= at91rm9200.o at91rm9200_time.o at91rm9200_devices.o
diff --git a/arch/arm/mach-at91/sam9_rst.c b/arch/arm/mach-at91/sam9_rst.c
new file mode 100644
index 000000000000..8f03576e698f
--- /dev/null
+++ b/arch/arm/mach-at91/sam9_rst.c
@@ -0,0 +1,72 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2019 Pengutronix, Ahmad Fatoum <a.fatoum@pengutronix.de>
+ */
+
+#include <common.h>
+#include <init.h>
+#include <io.h>
+#include <restart.h>
+#include <linux/clk.h>
+#include <mach/at91_rstc.h>
+
+struct at91sam9x_rst {
+	struct restart_handler restart;
+	void __iomem *base;
+};
+
+static void __noreturn at91sam9x_restart_soc(struct restart_handler *rst)
+{
+	struct at91sam9x_rst *priv = container_of(rst, struct at91sam9x_rst, restart);
+
+	writel(AT91_RSTC_PROCRST
+	       | AT91_RSTC_PERRST
+	       | AT91_RSTC_EXTRST
+	       | AT91_RSTC_KEY,
+	       priv->base + AT91_RSTC_CR);
+
+	hang();
+}
+
+static int at91sam9x_rst_probe(struct device_d *dev)
+{
+	struct at91sam9x_rst *priv;
+	struct resource *iores;
+	struct clk *clk;
+
+	iores = dev_request_mem_resource(dev, 0);
+	if (IS_ERR(iores)) {
+		dev_err(dev, "could not get reset memory region\n");
+		return PTR_ERR(iores);
+	}
+
+	priv = xzalloc(sizeof(*priv));
+	priv->base = IOMEM(iores->start);
+
+	clk = clk_get(dev, NULL);
+	if (IS_ERR(clk)) {
+		release_region(iores);
+		free(priv);
+		return PTR_ERR(clk);
+	}
+
+	clk_enable(clk);
+
+	priv->restart.name = "at91sam9x-rst";
+	priv->restart.restart = at91sam9x_restart_soc;
+
+	return restart_handler_register(&priv->restart);
+}
+
+static const __maybe_unused struct of_device_id at91sam9x_rst_dt_ids[] = {
+	{ .compatible = "atmel,at91sam9g45-rstc", },
+	{ .compatible = "atmel,sama5d3-rstc", },
+	{ /* sentinel */ },
+};
+
+static struct driver_d at91sam9x_rst_driver = {
+	.name		= "at91sam9x-rst",
+	.of_compatible	= DRV_OF_COMPAT(at91sam9x_rst_dt_ids),
+	.probe		= at91sam9x_rst_probe,
+};
+device_platform_driver(at91sam9x_rst_driver);
-- 
2.25.1


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