sysreset: psci: support system reset in a generic way with PSCI

If the system is running PSCI firmware, the System Reset function
(func ID: 0x80000009) is supposed to be handled by PSCI, that is,
the SoC/board specific reset implementation should be moved to PSCI.
U-Boot should call the PSCI service according to the arm-smccc
manner.

The arm-smccc is supported on ARMv7 or later.  Especially, ARMv8
generation SoCs are likely to run ARM Trusted Firmware BL31.  In
this case, U-Boot is a non-secure world boot loader, so it should
not be able to reset the system directly.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>

arch/arm/Kconfig

@@ -177,6 +177,7 @@ config SYS_CACHELINE_SIZE
 config ARM_SMCCC
 	bool "Support for ARM SMC Calling Convention (SMCCC)"
 	depends on CPU_V7 || ARM64
+	select ARM_PSCI_FW
 	help
 	  Say Y here if you want to enable ARM SMC Calling Convention.
 	  This should be enabled if U-Boot needs to communicate with system

drivers/Kconfig

@@ -24,6 +24,8 @@ source "drivers/dfu/Kconfig"
 
 source "drivers/dma/Kconfig"
 
+source "drivers/firmware/Kconfig"
+
 source "drivers/fpga/Kconfig"
 
 source "drivers/gpio/Kconfig"

drivers/Makefile

@@ -23,7 +23,7 @@ obj-$(CONFIG_SPL_SERIAL_SUPPORT) += serial/
 obj-$(CONFIG_SPL_SPI_SUPPORT) += spi/
 obj-$(CONFIG_SPL_POWER_SUPPORT) += power/ power/pmic/
 obj-$(CONFIG_SPL_POWER_SUPPORT) += power/regulator/
-obj-$(CONFIG_SPL_DRIVERS_MISC_SUPPORT) += misc/ sysreset/
+obj-$(CONFIG_SPL_DRIVERS_MISC_SUPPORT) += misc/ sysreset/ firmware/
 obj-$(CONFIG_SPL_MTD_SUPPORT) += mtd/
 obj-$(CONFIG_SPL_NAND_SUPPORT) += mtd/nand/
 obj-$(CONFIG_SPL_ONENAND_SUPPORT) += mtd/onenand/
@@ -52,7 +52,7 @@ endif
 ifdef CONFIG_TPL_BUILD
 
 obj-$(CONFIG_TPL_I2C_SUPPORT) += i2c/
-obj-$(CONFIG_TPL_DRIVERS_MISC_SUPPORT) += misc/ sysreset/
+obj-$(CONFIG_TPL_DRIVERS_MISC_SUPPORT) += misc/ sysreset/ firmware/
 obj-$(CONFIG_TPL_MMC_SUPPORT) += mmc/
 obj-$(CONFIG_TPL_MPC8XXX_INIT_DDR_SUPPORT) += ddr/fsl/
 obj-$(CONFIG_TPL_NAND_SUPPORT) += mtd/nand/
@@ -71,6 +71,7 @@ obj-y += block/
 obj-$(CONFIG_BOOTCOUNT_LIMIT) += bootcount/
 obj-$(CONFIG_CPU) += cpu/
 obj-y += crypto/
+obj-y += firmware/
 obj-$(CONFIG_FPGA) += fpga/
 obj-y += hwmon/
 obj-y += misc/

drivers/firmware/Kconfig

@@ -0,0 +1,6 @@
+config FIRMWARE
+	bool
+
+config ARM_PSCI_FW
+	bool
+	select FIRMWARE

drivers/firmware/Makefile

@@ -0,0 +1,2 @@
+obj-$(CONFIG_FIRMWARE)		+= firmware-uclass.o
+obj-$(CONFIG_ARM_PSCI_FW)	+= psci.o

drivers/firmware/firmware-uclass.c

@@ -0,0 +1,11 @@
+/*
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <dm/uclass.h>
+
+/* Firmware access is platform-dependent.  No generic code in uclass */
+UCLASS_DRIVER(firmware) = {
+	.id		= UCLASS_FIRMWARE,
+	.name		= "firmware",
+};

drivers/firmware/psci.c

@@ -0,0 +1,94 @@
+/*
+ * Copyright (C) 2017 Masahiro Yamada <yamada.masahiro@socionext.com>
+ *
+ * Based on drivers/firmware/psci.c from Linux:
+ * Copyright (C) 2015 ARM Limited
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <common.h>
+#include <dm/device.h>
+#include <dm/lists.h>
+#include <libfdt.h>
+#include <linux/arm-smccc.h>
+#include <linux/errno.h>
+#include <linux/psci.h>
+
+psci_fn *invoke_psci_fn;
+
+static unsigned long __invoke_psci_fn_hvc(unsigned long function_id,
+			unsigned long arg0, unsigned long arg1,
+			unsigned long arg2)
+{
+	struct arm_smccc_res res;
+
+	arm_smccc_hvc(function_id, arg0, arg1, arg2, 0, 0, 0, 0, &res);
+	return res.a0;
+}
+
+static unsigned long __invoke_psci_fn_smc(unsigned long function_id,
+			unsigned long arg0, unsigned long arg1,
+			unsigned long arg2)
+{
+	struct arm_smccc_res res;
+
+	arm_smccc_smc(function_id, arg0, arg1, arg2, 0, 0, 0, 0, &res);
+	return res.a0;
+}
+
+static int psci_bind(struct udevice *dev)
+{
+	/* No SYSTEM_RESET support for PSCI 0.1 */
+	if (of_device_is_compatible(dev, "arm,psci-0.2") ||
+	    of_device_is_compatible(dev, "arm,psci-1.0")) {
+		int ret;
+
+		/* bind psci-sysreset optionally */
+		ret = device_bind_driver(dev, "psci-sysreset", "psci-sysreset",
+					 NULL);
+		if (ret)
+			debug("PSCI System Reset was not bound.\n");
+	}
+
+	return 0;
+}
+
+static int psci_probe(struct udevice *dev)
+{
+	DECLARE_GLOBAL_DATA_PTR;
+	const char *method;
+
+	method = fdt_stringlist_get(gd->fdt_blob, dev->of_offset, "method", 0,
+				    NULL);
+	if (!method) {
+		printf("missing \"method\" property\n");
+		return -ENXIO;
+	}
+
+	if (!strcmp("hvc", method)) {
+		invoke_psci_fn = __invoke_psci_fn_hvc;
+	} else if (!strcmp("smc", method)) {
+		invoke_psci_fn = __invoke_psci_fn_smc;
+	} else {
+		printf("invalid \"method\" property: %s\n", method);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static const struct udevice_id psci_of_match[] = {
+	{ .compatible = "arm,psci" },
+	{ .compatible = "arm,psci-0.2" },
+	{ .compatible = "arm,psci-1.0" },
+	{},
+};
+
+U_BOOT_DRIVER(psci) = {
+	.name = "psci",
+	.id = UCLASS_FIRMWARE,
+	.of_match = psci_of_match,
+	.bind = psci_bind,
+	.probe = psci_probe,
+};

drivers/sysreset/Kconfig

@@ -13,4 +13,14 @@ config SYSRESET
 	  to effect a reset. The uclass will try all available drivers when
 	  reset_walk() is called.
 
+if SYSRESET
+
+config SYSRESET_PSCI
+	bool "Enable support for PSCI System Reset"
+	depends on ARM_PSCI_FW
+	help
+	  Enable PSCI SYSTEM_RESET function call.  To use this, PSCI firmware
+	  must be running on your system.
+
+endif
 endmenu

drivers/sysreset/Makefile

@@ -5,6 +5,7 @@
 #
 
 obj-$(CONFIG_SYSRESET) += sysreset-uclass.o
+obj-$(CONFIG_SYSRESET_PSCI) += sysreset_psci.o
 
 ifndef CONFIG_SPL_BUILD
 obj-$(CONFIG_ROCKCHIP_RK3036) += sysreset_rk3036.o

drivers/sysreset/sysreset_psci.c

@@ -0,0 +1,41 @@
+/*
+ * Copyright (C) 2017 Masahiro Yamada <yamada.masahiro@socionext.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <dm/device.h>
+#include <sysreset.h>
+#include <linux/errno.h>
+#include <linux/psci.h>
+
+static int psci_sysreset_request(struct udevice *dev, enum sysreset_t type)
+{
+	unsigned long function_id;
+
+	switch (type) {
+	case SYSRESET_WARM:
+	case SYSRESET_COLD:
+		function_id = PSCI_0_2_FN_SYSTEM_RESET;
+		break;
+	case SYSRESET_POWER:
+		function_id = PSCI_0_2_FN_SYSTEM_OFF;
+		break;
+	default:
+		return -ENOSYS;
+	}
+
+	invoke_psci_fn(function_id, 0, 0, 0);
+
+	return -EINPROGRESS;
+}
+
+static struct sysreset_ops psci_sysreset_ops = {
+	.request = psci_sysreset_request,
+};
+
+U_BOOT_DRIVER(psci_sysreset) = {
+	.name = "psci-sysreset",
+	.id = UCLASS_SYSRESET,
+	.ops = &psci_sysreset_ops,
+};

include/dm/uclass-id.h

@@ -35,6 +35,7 @@ enum uclass_id {
 	UCLASS_DMA,		/* Direct Memory Access */
 	UCLASS_ETH,		/* Ethernet device */
 	UCLASS_GPIO,		/* Bank of general-purpose I/O pins */
+	UCLASS_FIRMWARE,	/* Firmware */
 	UCLASS_I2C,		/* I2C bus */
 	UCLASS_I2C_EEPROM,	/* I2C EEPROM device */
 	UCLASS_I2C_GENERIC,	/* Generic I2C device */

include/linux/psci.h

@@ -87,4 +87,17 @@
 #define PSCI_RET_NOT_PRESENT			-7
 #define PSCI_RET_DISABLED			-8
 
+#ifdef CONFIG_ARM_PSCI_FW
+typedef unsigned long (psci_fn)(unsigned long, unsigned long,
+				unsigned long, unsigned long);
+
+extern psci_fn *invoke_psci_fn;
+#else
+unsigned long invoke_psci_fn(unsigned long a0, unsigned long a1,
+			     unsigned long a2, unsigned long a3)
+{
+	return PSCI_RET_DISABLED;
+}
+#endif
+
 #endif /* _UAPI_LINUX_PSCI_H */