driver: watchdog: add sp805 watchdog support

sp805 is watchdog on some NXP layerscape SoCs, adding
it's driver. Configs CONFIG_WDT_SP805, CONFIG_WDT, CONFIG_CMD_WDT
needs to be enabled to use it.

Signed-off-by: Zhao Qiang <qiang.zhao@nxp.com>
Reviewed-by: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>

MAINTAINERS

@@ -519,6 +519,7 @@ FREESCALE QORIQ
 M:	Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>
 S:	Maintained
 T:	git git://git.denx.de/u-boot-fsl-qoriq.git
+F:	drivers/watchdog/sp805_wdt.c
 
 I2C
 M:	Heiko Schocher <hs@denx.de>

drivers/watchdog/Kconfig

@@ -103,6 +103,13 @@ config WDT_ORION
 	   Select this to enable Orion watchdog timer, which can be found on some
 	   Marvell Armada chips.
 
+config WDT_SP805
+	bool "SP805 watchdog timer support"
+	depends on WDT
+	help
+	   Select this to enable SP805 watchdog timer, which can be found on some
+	   nxp layerscape chips.
+
 config WDT_CDNS
 	bool "Cadence watchdog timer support"
 	depends on WDT

drivers/watchdog/Makefile

@@ -27,3 +27,4 @@ obj-$(CONFIG_WDT_CDNS) += cdns_wdt.o
 obj-$(CONFIG_WDT_MPC8xx) += mpc8xx_wdt.o
 obj-$(CONFIG_WDT_MT7621) += mt7621_wdt.o
 obj-$(CONFIG_WDT_MTK) += mtk_wdt.o
+obj-$(CONFIG_WDT_SP805) += sp805_wdt.o

drivers/watchdog/sp805_wdt.c

@@ -0,0 +1,127 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Watchdog driver for SP805 on some Layerscape SoC
+ *
+ * Copyright 2019 NXP
+ */
+
+#include <asm/io.h>
+#include <common.h>
+#include <dm/device.h>
+#include <dm/fdtaddr.h>
+#include <dm/read.h>
+#include <linux/bitops.h>
+#include <watchdog.h>
+#include <wdt.h>
+
+#define WDTLOAD			0x000
+#define WDTCONTROL		0x008
+#define WDTINTCLR		0x00C
+#define WDTLOCK			0xC00
+
+#define TIME_OUT_MIN_MSECS	1
+#define TIME_OUT_MAX_MSECS	120000
+#define SYS_FSL_WDT_CLK_DIV	16
+#define INT_ENABLE		BIT(0)
+#define RESET_ENABLE		BIT(1)
+#define DISABLE			0
+#define UNLOCK			0x1ACCE551
+#define LOCK			0x00000001
+#define INT_MASK		BIT(0)
+
+DECLARE_GLOBAL_DATA_PTR;
+
+struct sp805_wdt_priv {
+	void __iomem *reg;
+};
+
+static int sp805_wdt_reset(struct udevice *dev)
+{
+	struct sp805_wdt_priv *priv = dev_get_priv(dev);
+
+	writel(UNLOCK, priv->reg + WDTLOCK);
+	writel(INT_MASK, priv->reg + WDTINTCLR);
+	writel(LOCK, priv->reg + WDTLOCK);
+	readl(priv->reg + WDTLOCK);
+
+	return 0;
+}
+
+static int sp805_wdt_start(struct udevice *dev, u64 timeout, ulong flags)
+{
+	u32 load_value;
+	u32 load_time;
+	struct sp805_wdt_priv *priv = dev_get_priv(dev);
+
+	load_time = (u32)timeout;
+	if (timeout < TIME_OUT_MIN_MSECS)
+		load_time = TIME_OUT_MIN_MSECS;
+	else if (timeout > TIME_OUT_MAX_MSECS)
+		load_time = TIME_OUT_MAX_MSECS;
+	/* sp805 runs counter with given value twice, so when the max timeout is
+	 * set 120s, the gd->bus_clk is less than 1145MHz, the load_value will
+	 * not overflow.
+	 */
+	load_value = (gd->bus_clk) /
+		(2 * 1000 * SYS_FSL_WDT_CLK_DIV) * load_time;
+
+	writel(UNLOCK, priv->reg + WDTLOCK);
+	writel(load_value, priv->reg + WDTLOAD);
+	writel(INT_MASK, priv->reg + WDTINTCLR);
+	writel(INT_ENABLE | RESET_ENABLE, priv->reg + WDTCONTROL);
+	writel(LOCK, priv->reg + WDTLOCK);
+	readl(priv->reg + WDTLOCK);
+
+	return 0;
+}
+
+static int sp805_wdt_stop(struct udevice *dev)
+{
+	struct sp805_wdt_priv *priv = dev_get_priv(dev);
+
+	writel(UNLOCK, priv->reg + WDTLOCK);
+	writel(DISABLE, priv->reg + WDTCONTROL);
+	writel(LOCK, priv->reg + WDTLOCK);
+	readl(priv->reg + WDTLOCK);
+
+	return 0;
+}
+
+static int sp805_wdt_probe(struct udevice *dev)
+{
+	debug("%s: Probing wdt%u\n", __func__, dev->seq);
+
+	return 0;
+}
+
+static int sp805_wdt_ofdata_to_platdata(struct udevice *dev)
+{
+	struct sp805_wdt_priv *priv = dev_get_priv(dev);
+
+	priv->reg = (void __iomem *)dev_read_addr(dev);
+	if (IS_ERR(priv->reg))
+		return PTR_ERR(priv->reg);
+
+	return 0;
+}
+
+static const struct wdt_ops sp805_wdt_ops = {
+	.start = sp805_wdt_start,
+	.reset = sp805_wdt_reset,
+	.stop = sp805_wdt_stop,
+};
+
+static const struct udevice_id sp805_wdt_ids[] = {
+	{ .compatible = "arm,sp805-wdt" },
+	{}
+};
+
+U_BOOT_DRIVER(sp805_wdt) = {
+	.name = "sp805_wdt",
+	.id = UCLASS_WDT,
+	.of_match = sp805_wdt_ids,
+	.probe = sp805_wdt_probe,
+	.priv_auto_alloc_size = sizeof(struct sp805_wdt_priv),
+	.ofdata_to_platdata = sp805_wdt_ofdata_to_platdata,
+	.ops = &sp805_wdt_ops,
+};