clocksource: add samsung pwm timer driver

This adds a new clocksource driver for the PWM timer that is
present in most Samsung SoCs, based on the existing driver in
arch/arm/plat-samsung/samsung-time.c and many changes implemented by
Tomasz Figa.

Originally, the conversion of all Samsung machines to the new driver was
planned for 3.10, but that work ended up being too late and too invasive
just before the merge window.

Unfortunately, other changes in the Exynos platform resulted in some
Exynos4 setups, particularly the Universal C210 board to be broken. In
order to fix that with minimum risk, so we now leave the existing pwm
clocksource driver in place for all older platforms and use the new
driver only for device tree enabled boards. This way, we can get the
broken machines running again using DT descriptions.

All clocksource changes were implemented by Tomasz, while the DT
registration was rewritten by Arnd.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Tomasz Figa <t.figa@samsung.com>
Cc: Kyungmin Park <kyungmin.park@samsung.com>
Cc: Kukjin Kim <kgene.kim@samsung.com>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>

drivers/clocksource/Kconfig

@@ -67,3 +67,13 @@ config CLKSRC_METAG_GENERIC
 	def_bool y if METAG
 	help
 	  This option enables support for the Meta per-thread timers.
+
+config CLKSRC_SAMSUNG_PWM
+	def_bool ARCH_EXYNOS4
+	depends on OF
+	select CLKSRC_MMIO
+	help
+	  This is a new clocksource driver for the PWM timer found in
+	  Samsung S3C, S5P and Exynos SoCs, replacing an earlier driver
+	  for all devicetree enabled platforms. This driver will be
+	  needed only on systems that do not have the Exynos MCT available.

drivers/clocksource/Makefile

@@ -19,6 +19,7 @@ obj-$(CONFIG_ARCH_BCM2835)	+= bcm2835_timer.o
 obj-$(CONFIG_SUNXI_TIMER)	+= sunxi_timer.o
 obj-$(CONFIG_ARCH_TEGRA)	+= tegra20_timer.o
 obj-$(CONFIG_VT8500_TIMER)	+= vt8500_timer.o
+obj-$(CONFIG_CLKSRC_SAMSUNG_PWM)	+= samsung_pwm_timer.o
 
 obj-$(CONFIG_ARM_ARCH_TIMER)		+= arm_arch_timer.o
 obj-$(CONFIG_CLKSRC_METAG_GENERIC)	+= metag_generic.o

include/clocksource/samsung_pwm.h

+/*
+ * Copyright (C) 2013 Samsung Electronics Co., Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#ifndef __CLOCKSOURCE_SAMSUNG_PWM_H
+#define __CLOCKSOURCE_SAMSUNG_PWM_H
+
+#include <linux/spinlock.h>
+
+#define SAMSUNG_PWM_NUM		5
+
+struct platform_device;
+struct device_node;
+
+struct samsung_pwm_variant {
+	u8 bits;
+	u8 div_base;
+	u8 tclk_mask;
+	u8 output_mask;
+	bool has_tint_cstat;
+};
+
+struct samsung_pwm {
+	struct samsung_pwm_variant variant;
+	spinlock_t slock;
+	void __iomem *base;
+	int irq[SAMSUNG_PWM_NUM];
+};
+
+#endif /* __CLOCKSOURCE_SAMSUNG_PWM_H */