microblaze: Convert axi timer to DM driver

Move axi timer driver from Microblaze to generic location.
Origin implementation was irq based with counting down timer.

CONFIG_TIMER drivers are designed differently that timer is free running up
timer with automatic reload without any interrupt.
Information about clock rates are find out in timer_pre_probe() that's why
there is no need to get any additional information from DT in the driver
itself (only register offset).

Signed-off-by: Michal Simek <michal.simek@amd.com>
Tested-by: Ovidiu Panait <ovidiu.panait@windriver.com>
Link: https://lore.kernel.org/r/6c12fc86bbc1f17d05c25018862e7b7b03346b36.1654684731.git.michal.simek@amd.com

drivers/timer/Kconfig

@@ -272,4 +272,12 @@ config IMX_GPT_TIMER
 	  Select this to enable support for the timer found on
 	  NXP i.MX devices.
 
+config XILINX_TIMER
+	bool "Xilinx timer support"
+	depends on TIMER
+	select REGMAP
+	help
+	  Select this to enable support for the timer found on
+	  any Xilinx boards (axi timer).
+
 endmenu

drivers/timer/Makefile

@@ -27,3 +27,4 @@ obj-$(CONFIG_X86_TSC_TIMER)	+= tsc_timer.o
 obj-$(CONFIG_MTK_TIMER)		+= mtk_timer.o
 obj-$(CONFIG_MCHP_PIT64B_TIMER)	+= mchp-pit64b-timer.o
 obj-$(CONFIG_IMX_GPT_TIMER)	+= imx-gpt-timer.o
+obj-$(CONFIG_XILINX_TIMER)	+= xilinx-timer.o

drivers/timer/xilinx-timer.c

@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * (C) Copyright 2022 Advanced Micro Devices, Inc
+ * Michal Simek <michal.simek@amd.com>
+ *
+ * (C) Copyright 2007 Michal Simek
+ * Michal SIMEK <monstr@monstr.eu>
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <timer.h>
+#include <regmap.h>
+#include <dm/device_compat.h>
+
+#define TIMER_ENABLE_ALL    0x400 /* ENALL */
+#define TIMER_PWM           0x200 /* PWMA0 */
+#define TIMER_INTERRUPT     0x100 /* T0INT */
+#define TIMER_ENABLE        0x080 /* ENT0 */
+#define TIMER_ENABLE_INTR   0x040 /* ENIT0 */
+#define TIMER_RESET         0x020 /* LOAD0 */
+#define TIMER_RELOAD        0x010 /* ARHT0 */
+#define TIMER_EXT_CAPTURE   0x008 /* CAPT0 */
+#define TIMER_EXT_COMPARE   0x004 /* GENT0 */
+#define TIMER_DOWN_COUNT    0x002 /* UDT0 */
+#define TIMER_CAPTURE_MODE  0x001 /* MDT0 */
+
+#define TIMER_CONTROL_OFFSET	0
+#define TIMER_LOADREG_OFFSET	4
+#define TIMER_COUNTER_OFFSET	8
+
+struct xilinx_timer_priv {
+	struct regmap *regs;
+};
+
+static u64 xilinx_timer_get_count(struct udevice *dev)
+{
+	struct xilinx_timer_priv *priv = dev_get_priv(dev);
+	u32 value;
+
+	regmap_read(priv->regs, TIMER_COUNTER_OFFSET, &value);
+
+	return value;
+}
+
+static int xilinx_timer_probe(struct udevice *dev)
+{
+	struct xilinx_timer_priv *priv = dev_get_priv(dev);
+	int ret;
+
+	/* uc_priv->clock_rate has already clock rate */
+	ret = regmap_init_mem(dev_ofnode(dev), &priv->regs);
+	if (ret) {
+		dev_dbg(dev, "failed to get regbase of timer\n");
+		return ret;
+	}
+
+	regmap_write(priv->regs, TIMER_LOADREG_OFFSET, 0);
+	regmap_write(priv->regs, TIMER_CONTROL_OFFSET, TIMER_RESET);
+	regmap_write(priv->regs, TIMER_CONTROL_OFFSET,
+		     TIMER_ENABLE | TIMER_RELOAD);
+
+	return 0;
+}
+
+static const struct timer_ops xilinx_timer_ops = {
+	.get_count = xilinx_timer_get_count,
+};
+
+static const struct udevice_id xilinx_timer_ids[] = {
+	{ .compatible = "xlnx,xps-timer-1.00.a" },
+	{}
+};
+
+U_BOOT_DRIVER(xilinx_timer) = {
+	.name = "xilinx_timer",
+	.id = UCLASS_TIMER,
+	.of_match = xilinx_timer_ids,
+	.priv_auto = sizeof(struct xilinx_timer_priv),
+	.probe = xilinx_timer_probe,
+	.ops = &xilinx_timer_ops,
+};