[PATCH 1/2] pwm: lpss: Make builtin and add lookup-table so that i915 can find the pwm_backlight

[Hans de Goede]

The primary consumer of the lpss pwm is the i915 kms driver, but
currently that driver cannot get the pwm because i915 platforms are
not using devicetree and pwm-lpss does not call pwm_add_table.

Another problem is that i915 does not support get_pwm returning
-EPROBE_DEFER and i915's init is very complex and this is almost
impossible to fix.

This commit changes the PWM_LPSS Kconfig from a tristate to a bool, so
that when the i915 driver loads the lpss pwm will be available avoiding
the -EPROBE_DEFER issue. Note that this is identical to how the same
problem was solved for the pwm-crc driver.

Being builtin also allows calling pwm_add_table directly from the
pwm-lpss code, otherwise the pwm_add_table call would need to be put
somewhere else to ensure it happens before i915 calls pwm_get,
even if i915 would support -EPROBE_DEFER.

Signed-off-by: Hans de Goede <hdegoede at redhat.com>
---
 drivers/pwm/Kconfig    | 12 +++---------
 drivers/pwm/pwm-lpss.c | 11 +++++++++++
 2 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index bf01288..cda31ea 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -240,28 +240,22 @@ config PWM_LPC32XX
 	  will be called pwm-lpc32xx.
 
 config PWM_LPSS
-	tristate
+	bool
 
 config PWM_LPSS_PCI
-	tristate "Intel LPSS PWM PCI driver"
+	bool "Intel LPSS PWM PCI driver"
 	depends on X86 && PCI
 	select PWM_LPSS
 	help
 	  The PCI driver for Intel Low Power Subsystem PWM controller.
 
-	  To compile this driver as a module, choose M here: the module
-	  will be called pwm-lpss-pci.
-
 config PWM_LPSS_PLATFORM
-	tristate "Intel LPSS PWM platform driver"
+	bool "Intel LPSS PWM platform driver"
 	depends on X86 && ACPI
 	select PWM_LPSS
 	help
 	  The platform driver for Intel Low Power Subsystem PWM controller.
 
-	  To compile this driver as a module, choose M here: the module
-	  will be called pwm-lpss-platform.
-
 config PWM_MESON
 	tristate "Amlogic Meson PWM driver"
 	depends on ARCH_MESON
diff --git a/drivers/pwm/pwm-lpss.c b/drivers/pwm/pwm-lpss.c
index 72c0bce..b4d8835 100644
--- a/drivers/pwm/pwm-lpss.c
+++ b/drivers/pwm/pwm-lpss.c
@@ -161,6 +161,12 @@ static const struct pwm_ops pwm_lpss_ops = {
 	.owner = THIS_MODULE,
 };
 
+/* PWM consumed by the Intel GFX */
+static struct pwm_lookup pwm_lpss_lookup[] = {
+	PWM_LOOKUP("pwm-lpss", 0, "0000:00:02.0", "pwm_backlight", 0,
+		   PWM_POLARITY_NORMAL),
+};
+
 struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
 				     const struct pwm_lpss_boardinfo *info)
 {
@@ -193,12 +199,17 @@ struct pwm_lpss_chip *pwm_lpss_probe(struct device *dev, struct resource *r,
 		return ERR_PTR(ret);
 	}
 
+	/* Add lookup table for pwm_backlight */
+	pwm_lpss_lookup[0].provider = dev_name(dev);
+	pwm_add_table(pwm_lpss_lookup, ARRAY_SIZE(pwm_lpss_lookup));
+
 	return lpwm;
 }
 EXPORT_SYMBOL_GPL(pwm_lpss_probe);
 
 int pwm_lpss_remove(struct pwm_lpss_chip *lpwm)
 {
+	pwm_remove_table(pwm_lpss_lookup, ARRAY_SIZE(pwm_lpss_lookup));
 	return pwmchip_remove(&lpwm->chip);
 }
 EXPORT_SYMBOL_GPL(pwm_lpss_remove);
-- 
2.9.3