pwm: Add new pwm-samsung driver

This patch introduces new Samsung PWM driver, which is completely
rewritten to be multiplatform- and DeviceTree-aware.

In addition, remaining problems of old driver are fixed, such as:
 - proper handling of hardware variants,
 - synchronization on SMP systems,
 - handling of boundary parameter values,
 - hardware sharing with PWM clocksource driver,
 - undefined state of PWM output after stopping PWM channel.

Signed-off-by: Tomasz Figa <tomasz.figa@gmail.com>
Reviewed-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Tested-by: Mark Brown <broonie@linaro.org>
Tested-by: Sylwester Nawrocki <sylvester.nawrocki@gmail.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: Thierry Reding <thierry.reding@gmail.com>

1 files changed, 7 insertions, 0 deletions

diff --git a/include/clocksource/samsung_pwm.h b/include/clocksource/samsung_pwm.h
index 5c449c8199e9..0c7d48b8b396 100644
--- a/include/clocksource/samsung_pwm.h
+++ b/include/clocksource/samsung_pwm.h
@@ -20,7 +20,14 @@
 
 #define SAMSUNG_PWM_NUM         5
 
+/*
+ * Following declaration must be in an ifdef due to this symbol being static
+ * in pwm-samsung driver if the clocksource driver is not compiled in and the
+ * spinlock is not shared between both drivers.
+ */
+#ifdef CONFIG_CLKSRC_SAMSUNG_PWM
 extern spinlock_t samsung_pwm_lock;
+#endif
 
 struct samsung_pwm_variant {
         u8 bits;