hammer: Enable PWM output for keyboard backlight

BRANCH=none
BUG=chrome-os-partner:59083
TEST=make BOARD=hammer -j

Change-Id: Ibbf82c6c0f8115cbf611c74fc0585e97850d2019
Reviewed-on: https://chromium-review.googlesource.com/430575
Commit-Ready: Nicolas Boichat <drinkcat@chromium.org>
Tested-by: Nicolas Boichat <drinkcat@chromium.org>
Reviewed-by: Vincent Palatin <vpalatin@chromium.org>

board/hammer/board.c

@@ -11,6 +11,8 @@
 #include "hooks.h"
 #include "i2c.h"
 #include "keyboard_raw.h"
+#include "pwm.h"
+#include "pwm_chip.h"
 #include "registers.h"
 #include "task.h"
 #include "update_fw.h"
@@ -47,6 +49,12 @@ const struct i2c_port_t i2c_ports[] = {
 };
 const unsigned int i2c_ports_used = ARRAY_SIZE(i2c_ports);
 
+/* PWM channels. Must be in the exactly same order as in enum pwm_channel. */
+const struct pwm_t pwm_channels[] = {
+	{STM32_TIM(TIM_KBLIGHT), STM32_TIM_CH(1), 0, 100 /* Hz */ },
+};
+BUILD_ASSERT(ARRAY_SIZE(pwm_channels) == PWM_CH_COUNT);
+
 /******************************************************************************
  * Support firmware upgrade over USB. We can update whichever section is not
  * the current section.

board/hammer/board.h

@@ -70,6 +70,9 @@
 #define CONFIG_I2C_MASTER
 #define I2C_PORT_MASTER 0
 
+/* Enable PWM */
+#define CONFIG_PWM
+
 /* Sign and switch to RW partition on boot. */
 #define CONFIG_RWSIG
 #define CONFIG_RSA
@@ -86,7 +89,8 @@
 
 /* Timer selection */
 #define TIM_CLOCK32 2
-#define TIM_WATCHDOG 17
+#define TIM_WATCHDOG 16
+#define TIM_KBLIGHT 17
 
 #include "gpio_signal.h"
 
@@ -101,5 +105,11 @@ enum usb_strings {
 	USB_STR_COUNT
 };
 
+enum pwm_channel {
+	PWM_CH_KBLIGHT = 0,
+	/* Number of PWM channels */
+	PWM_CH_COUNT
+};
+
 #endif /* !__ASSEMBLER__ */
 #endif /* __CROS_EC_BOARD_H */