pwm: pwm-tiecap: Low power sleep support

In low power modes of AM33XX platforms, peripherals power is cut off.
This patch supports low power sleep transition support for ECAP driver.

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

1 files changed, 53 insertions, 0 deletions

diff --git a/drivers/pwm/pwm-tiecap.c b/drivers/pwm/pwm-tiecap.c
index 5cf016dd9822..05b676db88e6 100644
--- a/drivers/pwm/pwm-tiecap.c
+++ b/drivers/pwm/pwm-tiecap.c
@@ -41,10 +41,17 @@
 #define ECCTL2_SYNC_SEL_DISA    (BIT(7) | BIT(6))
 #define ECCTL2_TSCTR_FREERUN    BIT(4)
 
+struct ecap_context {
+        u32     cap3;
+        u32     cap4;
+        u16     ecctl2;
+};
+
 struct ecap_pwm_chip {
         struct pwm_chip chip;
         unsigned int    clk_rate;
         void __iomem    *mmio_base;
+        struct ecap_context ctx;
 };
 
 static inline struct ecap_pwm_chip *to_ecap_pwm_chip(struct pwm_chip *chip)
@@ -288,11 +295,57 @@ static int ecap_pwm_remove(struct platform_device *pdev)
         return pwmchip_remove(&pc->chip);
 }
 
+void ecap_pwm_save_context(struct ecap_pwm_chip *pc)
+{
+        pm_runtime_get_sync(pc->chip.dev);
+        pc->ctx.ecctl2 = readw(pc->mmio_base + ECCTL2);
+        pc->ctx.cap4 = readl(pc->mmio_base + CAP4);
+        pc->ctx.cap3 = readl(pc->mmio_base + CAP3);
+        pm_runtime_put_sync(pc->chip.dev);
+}
+
+void ecap_pwm_restore_context(struct ecap_pwm_chip *pc)
+{
+        writel(pc->ctx.cap3, pc->mmio_base + CAP3);
+        writel(pc->ctx.cap4, pc->mmio_base + CAP4);
+        writew(pc->ctx.ecctl2, pc->mmio_base + ECCTL2);
+}
+
+static int ecap_pwm_suspend(struct device *dev)
+{
+        struct ecap_pwm_chip *pc = dev_get_drvdata(dev);
+        struct pwm_device *pwm = pc->chip.pwms;
+
+        ecap_pwm_save_context(pc);
+
+        /* Disable explicitly if PWM is running */
+        if (test_bit(PWMF_ENABLED, &pwm->flags))
+                pm_runtime_put_sync(dev);
+
+        return 0;
+}
+
+static int ecap_pwm_resume(struct device *dev)
+{
+        struct ecap_pwm_chip *pc = dev_get_drvdata(dev);
+        struct pwm_device *pwm = pc->chip.pwms;
+
+        /* Enable explicitly if PWM was running */
+        if (test_bit(PWMF_ENABLED, &pwm->flags))
+                pm_runtime_get_sync(dev);
+
+        ecap_pwm_restore_context(pc);
+        return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(ecap_pwm_pm_ops, ecap_pwm_suspend, ecap_pwm_resume);
+
 static struct platform_driver ecap_pwm_driver = {
         .driver = {
                 .name   = "ecap",
                 .owner  = THIS_MODULE,
                 .of_match_table = ecap_of_match,
+                .pm     = &ecap_pwm_pm_ops,
         },
         .probe = ecap_pwm_probe,
         .remove = ecap_pwm_remove,