soc: ti: pm33xx: Add base cpuidle support

Some cpuidle C-states supported on am335x and am437x, like C1 on am335x,
require the use of the wkup_m3_ipc driver, and all C-states beyond C0 on
both platforms require the use of the SRAM sleep code.

Pass am33xx_do_sram_idle as the idle function to the platform pm core to
be used by the cpuidle-arm driver when entering cpuidle states.
am33xx_do_sram_idle will detect when the wkup_m3 is needed and ping it
if necessary before calling the final cpu_suspend op which will execute
the SRAM code to put the cpu into idle.

Finally, use the begin_suspend and finish_suspend platform ops to be
called at the beginning and end of suspend path to allow use of
cpu_idle_poll_ctrl.

This prevents races between cpuidle and suspend paths trying to
communicate with the wkup_m3, as during suspend we only want it
configured for entry to suspend.
Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Acked-by: Santosh Shilimkar <ssantosh@kernel.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>

drivers/soc/ti/pm33xx.c

@@ -130,6 +130,19 @@ static int am33xx_push_sram_idle(void)
 	return 0;
 }
 
+static int am33xx_do_sram_idle(u32 wfi_flags)
+{
+	int ret = 0;
+
+	if (!m3_ipc || !pm_ops)
+		return 0;
+
+	if (wfi_flags & WFI_FLAG_WAKE_M3)
+		ret = m3_ipc->ops->prepare_low_power(m3_ipc, WKUP_M3_IDLE);
+
+	return pm_ops->cpu_suspend(am33xx_do_wfi_sram, wfi_flags);
+}
+
 static int __init am43xx_map_gic(void)
 {
 	gic_dist_base = ioremap(AM43XX_GIC_DIST_BASE, SZ_4K);
@@ -260,6 +273,8 @@ static int am33xx_pm_begin(suspend_state_t state)
 		rtc_only_idle = 0;
 	}
 
+	pm_ops->begin_suspend();
+
 	switch (state) {
 	case PM_SUSPEND_MEM:
 		ret = m3_ipc->ops->prepare_low_power(m3_ipc, WKUP_M3_DEEPSLEEP);
@@ -301,6 +316,8 @@ static void am33xx_pm_end(void)
 	}
 
 	rtc_only_idle = 0;
+
+	pm_ops->finish_suspend();
 }
 
 static int am33xx_pm_valid(suspend_state_t state)
@@ -503,7 +520,7 @@ static int am33xx_pm_probe(struct platform_device *pdev)
 	suspend_wfi_flags |= WFI_FLAG_WAKE_M3;
 #endif /* CONFIG_SUSPEND */
 
-	ret = pm_ops->init(NULL);
+	ret = pm_ops->init(am33xx_do_sram_idle);
 	if (ret) {
 		dev_err(dev, "Unable to call core pm init!\n");
 		ret = -ENODEV;
@@ -522,6 +539,8 @@ static int am33xx_pm_probe(struct platform_device *pdev)
 
 static int am33xx_pm_remove(struct platform_device *pdev)
 {
+	if (pm_ops->deinit)
+		pm_ops->deinit();
 	suspend_set_ops(NULL);
 	wkup_m3_ipc_put(m3_ipc);
 	am33xx_pm_free_sram();