1 files changed, 60 insertions, 0 deletions
diff --git a/include/linux/platform_data/x86/pwm-lpss.h b/include/linux/platform_data/x86/pwm-lpss.h
new file mode 100644
index 000000000000..f0349edb47f4
--- /dev/null
+++ b/include/linux/platform_data/x86/pwm-lpss.h
@@ -0,0 +1,60 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/* Intel Low Power Subsystem PWM controller driver */
+
+#ifndef __PLATFORM_DATA_X86_PWM_LPSS_H
+#define __PLATFORM_DATA_X86_PWM_LPSS_H
+
+#include <linux/types.h>
+
+struct device;
+
+struct pwm_lpss_chip;
+
+struct pwm_lpss_boardinfo {
+	unsigned long clk_rate;
+	unsigned int npwm;
+	unsigned long base_unit_bits;
+	/*
+	 * NOTE:
+	 * Intel Broxton, Apollo Lake, and Gemini Lake have different programming flow.
+	 *
+	 * Initial Enable or First Activation
+	 * 1. Program the base unit and on time divisor values.
+	 * 2. Set the software update bit.
+	 * 3. Poll in a loop on the PWMCTRL bit until software update bit is cleared.+
+	 * 4. Enable the PWM output by setting PWM Enable.
+	 * 5. Repeat the above steps for the next PWM Module.
+	 *
+	 * Dynamic update while PWM is Enabled
+	 * 1. Program the base unit and on-time divisor values.
+	 * 2. Set the software update bit.
+	 * 3. Repeat the above steps for the next PWM module.
+	 *
+	 * + After setting PWMCTRL register's SW update bit, hardware automatically
+	 * deasserts the SW update bit after a brief delay. It was observed that
+	 * setting of PWM enable is typically done via read-modify-write of the PWMCTRL
+	 * register. If there is no/little delay between setting software update bit
+	 * and setting enable bit via read-modify-write, it is possible that the read
+	 * could return with software enable as 1. In that case, the last write to set
+	 * enable to 1 could also set sw_update to 1. If this happens, sw_update gets
+	 * stuck and the driver code can hang as it explicitly waits for sw_update bit
+	 * to be 0 after setting the enable bit to 1. To avoid this race condition,
+	 * SW should poll on the software update bit to make sure that it is 0 before
+	 * doing the read-modify-write to set the enable bit to 1.
+	 *
+	 * Also, we noted that if sw_update bit was set in step #1 above then when it
+	 * is set again in step #2, sw_update bit never gets cleared and the flow hangs.
+	 * As such, we need to make sure that sw_update bit is 0 when doing step #1.
+	 */
+	bool bypass;
+	/*
+	 * On some devices the _PS0/_PS3 AML code of the GPU (GFX0) device
+	 * messes with the PWM0 controllers state,
+	 */
+	bool other_devices_aml_touches_pwm_regs;
+};
+
+struct pwm_chip *devm_pwm_lpss_probe(struct device *dev, void __iomem *base,
+				     const struct pwm_lpss_boardinfo *info);
+
+#endif	/* __PLATFORM_DATA_X86_PWM_LPSS_H */