1/* SPDX-License-Identifier: GPL-2.0-only */
2/* Intel Low Power Subsystem PWM controller driver */
3
4#ifndef __PLATFORM_DATA_X86_PWM_LPSS_H
5#define __PLATFORM_DATA_X86_PWM_LPSS_H
6
7#include <linux/types.h>
8
9struct device;
10
11struct pwm_lpss_chip;
12
13struct pwm_lpss_boardinfo {
14 unsigned long clk_rate;
15 unsigned int npwm;
16 unsigned long base_unit_bits;
17 /*
18 * NOTE:
19 * Intel Broxton, Apollo Lake, and Gemini Lake have different programming flow.
20 *
21 * Initial Enable or First Activation
22 * 1. Program the base unit and on time divisor values.
23 * 2. Set the software update bit.
24 * 3. Poll in a loop on the PWMCTRL bit until software update bit is cleared.+
25 * 4. Enable the PWM output by setting PWM Enable.
26 * 5. Repeat the above steps for the next PWM Module.
27 *
28 * Dynamic update while PWM is Enabled
29 * 1. Program the base unit and on-time divisor values.
30 * 2. Set the software update bit.
31 * 3. Repeat the above steps for the next PWM module.
32 *
33 * + After setting PWMCTRL register's SW update bit, hardware automatically
34 * deasserts the SW update bit after a brief delay. It was observed that
35 * setting of PWM enable is typically done via read-modify-write of the PWMCTRL
36 * register. If there is no/little delay between setting software update bit
37 * and setting enable bit via read-modify-write, it is possible that the read
38 * could return with software enable as 1. In that case, the last write to set
39 * enable to 1 could also set sw_update to 1. If this happens, sw_update gets
40 * stuck and the driver code can hang as it explicitly waits for sw_update bit
41 * to be 0 after setting the enable bit to 1. To avoid this race condition,
42 * SW should poll on the software update bit to make sure that it is 0 before
43 * doing the read-modify-write to set the enable bit to 1.
44 *
45 * Also, we noted that if sw_update bit was set in step #1 above then when it
46 * is set again in step #2, sw_update bit never gets cleared and the flow hangs.
47 * As such, we need to make sure that sw_update bit is 0 when doing step #1.
48 */
49 bool bypass;
50 /*
51 * On some devices the _PS0/_PS3 AML code of the GPU (GFX0) device
52 * messes with the PWM0 controllers state,
53 */
54 bool other_devices_aml_touches_pwm_regs;
55};
56
57struct pwm_chip *devm_pwm_lpss_probe(struct device *dev, void __iomem *base,
58 const struct pwm_lpss_boardinfo *info);
59
60#endif /* __PLATFORM_DATA_X86_PWM_LPSS_H */
61

source code of linux/include/linux/platform_data/x86/pwm-lpss.h