boards/common/saml1x: enable PWM

The PWM for the on-board LED can only be used if xTimer is not sourced
from TC0_TC1.

boards/common/saml1x/Kconfig

@@ -9,6 +9,7 @@ config BOARD_COMMON_SAML1X
     select HAS_PERIPH_ADC
     select HAS_PERIPH_DAC
     select HAS_PERIPH_I2C
+    select HAS_PERIPH_PWM
     select HAS_PERIPH_RTC
     select HAS_PERIPH_RTT
     select HAS_PERIPH_SPI

boards/common/saml1x/Makefile.features

@@ -4,6 +4,7 @@ CPU = saml1x
 FEATURES_PROVIDED += periph_adc
 FEATURES_PROVIDED += periph_dac
 FEATURES_PROVIDED += periph_i2c
+FEATURES_PROVIDED += periph_pwm
 FEATURES_PROVIDED += periph_rtc
 FEATURES_PROVIDED += periph_rtt
 FEATURES_PROVIDED += periph_spi

boards/common/saml1x/include/periph_conf.h

@@ -103,6 +103,52 @@ static const uart_conf_t uart_config[] = {
 #define UART_NUMOF          ARRAY_SIZE(uart_config)
 /** @} */
 
+/**
+ * @name PWM configuration
+ * @{
+ */
+#define PWM_0_EN            1
+#define PWM_1_EN            0
+
+#if PWM_0_EN
+/* PWM0 channels */
+static const pwm_conf_chan_t pwm_chan0_config[] = {
+    /* GPIO pin, MUX value, TC channel */
+    { GPIO_PIN(PA, 18), GPIO_MUX_E, 0 },
+    { GPIO_PIN(PA, 19), GPIO_MUX_E, 1 },
+};
+#endif
+#if PWM_1_EN
+/* PWM1 channels */
+static const pwm_conf_chan_t pwm_chan1_config[] = {
+    /* GPIO pin, MUX value, TC channel */
+    { GPIO_PIN(PA, 7), GPIO_MUX_E, 1 }, /* LED */
+};
+#endif
+
+/* PWM device configuration */
+static const pwm_conf_t pwm_config[] = {
+#if PWM_0_EN
+    { .tim  = TC_CONFIG(TC2),
+      .chan = pwm_chan0_config,
+      .chan_numof = ARRAY_SIZE(pwm_chan0_config),
+      .gclk_src = SAM0_GCLK_MAIN,
+    },
+#endif
+#if PWM_1_EN
+    /* conflicts with xtimer config (TC0_TC1) */
+    { .tim  = TC_CONFIG(TC1),
+      .chan = pwm_chan1_config,
+      .chan_numof = ARRAY_SIZE(pwm_chan0_config),
+      .gclk_src = SAM0_GCLK_MAIN,
+    },
+#endif
+};
+
+/* number of devices that are actually defined */
+#define PWM_NUMOF           ARRAY_SIZE(pwm_config)
+/** @} */
+
 /**
  * @name    SPI configuration
  * @{