ACPI / LPSS: Call pwm_add_table() for Bay Trail PWM device

On Bay Trail systems with a Crystal Cove PMIC the Crystal Cove's PWM is
used to control the backlight brightness. On systems without one, the
Crystal Cove SoC's PWM is used and we need to call pwm_add_table() so
that the i915 driver can find the pwm for controlling the backlight.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpi_lpss.c

@@ -143,6 +143,22 @@ static void lpss_deassert_reset(struct lpss_private_data *pdata)
 	writel(val, pdata->mmio_base + offset);
 }
 
+/*
+ * BYT PWM used for backlight control by the i915 driver on systems without
+ * the Crystal Cove PMIC.
+ */
+static struct pwm_lookup byt_pwm_lookup[] = {
+	PWM_LOOKUP_WITH_MODULE("80860F09:00", 0, "0000:00:02.0",
+			       "pwm_backlight", 0, PWM_POLARITY_NORMAL,
+			       "pwm-lpss-platform"),
+};
+
+static void byt_pwm_setup(struct lpss_private_data *pdata)
+{
+	if (!acpi_dev_present("INT33FD", NULL, -1))
+		pwm_add_table(byt_pwm_lookup, ARRAY_SIZE(byt_pwm_lookup));
+}
+
 #define LPSS_I2C_ENABLE			0x6c
 
 static void byt_i2c_setup(struct lpss_private_data *pdata)
@@ -200,6 +216,7 @@ static const struct lpss_device_desc lpt_sdio_dev_desc = {
 
 static const struct lpss_device_desc byt_pwm_dev_desc = {
 	.flags = LPSS_SAVE_CTX,
+	.setup = byt_pwm_setup,
 };
 
 static const struct lpss_device_desc bsw_pwm_dev_desc = {