pwm: Add TI PWM subsystem driver

In some platforms (like am33xx), PWM sub modules (ECAP, EHRPWM, EQEP)
are integrated to PWM subsystem. These PWM submodules has resources
shared and only one register bit-field is provided to control
module/clock enable/disable, makes it difficult to handle common
resources from independent PWMSS submodule drivers.

So the solution here implemented in this patch is, to create driver for
PWMSS and take the role of parent driver for PWM submodules. PWMSS
parent driver enumerates all the child nodes under PWMSS module. Also
symbol "pwmss_submodule_state_change" exported to enable clock gating
for individual PWMSS submodules, and submodule drivers has to enable
clock gating from their drivers.

As this is only supported during DT boot, the parent/child relationship
is created and populated in DT execution flow. The only required change
is inside DTS file, making EHRPWM & ECAP as a child to PWMSS node.

Signed-off-by: Philip, Avinash <avinashphilip@ti.com>
Signed-off-by: Thierry Reding <thierry.reding@avionic-design.de>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 6e556c7da81e..3dcb76d86a97 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -136,6 +136,7 @@ config PWM_TEGRA
 config  PWM_TIECAP
         tristate "ECAP PWM support"
         depends on SOC_AM33XX
+        select PWM_TIPWMSS
         help
           PWM driver support for the ECAP APWM controller found on AM33XX
           TI SOC
@@ -146,6 +147,7 @@ config  PWM_TIECAP
 config  PWM_TIEHRPWM
         tristate "EHRPWM PWM support"
         depends on SOC_AM33XX
+        select PWM_TIPWMSS
         help
           PWM driver support for the EHRPWM controller found on AM33XX
           TI SOC
@@ -153,6 +155,15 @@ config  PWM_TIEHRPWM
           To compile this driver as a module, choose M here: the module
           will be called pwm-tiehrpwm.
 
+config  PWM_TIPWMSS
+        bool
+        depends on SOC_AM33XX && (PWM_TIEHRPWM || PWM_TIECAP)
+        help
+          PWM Subsystem driver support for AM33xx SOC.
+
+          PWM submodules require PWM config space access from submodule
+          drivers and require common parent driver support.
+
 config PWM_TWL6030
         tristate "TWL6030 PWM support"
         depends on TWL4030_CORE