linux-kernel - [PATCH RFC v1 6/8] drivers: qcom: cpu_pd: program next wakeup to PDC timer

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Date:   Thu, 11 Oct 2018 02:50:53 +0530
From:   "Raju P.L.S.S.S.N" <rplsssn@...eaurora.org>
To:     andy.gross@...aro.org, david.brown@...aro.org, rjw@...ysocki.net,
        ulf.hansson@...aro.org, khilman@...nel.org,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org
Cc:     rnayak@...eaurora.org, bjorn.andersson@...aro.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, sboyd@...nel.org, evgreen@...omium.org,
        dianders@...omium.org, mka@...omium.org, ilina@...eaurora.org,
        "Raju P.L.S.S.S.N" <rplsssn@...eaurora.org>
Subject: [PATCH RFC v1 6/8] drivers: qcom: cpu_pd: program next wakeup to PDC timer

In addition to sleep and wake request votes that need to be sent to
remote processor as part of low power mode entry, the next wake-up timer
value needs to be programmed to PDC (Power Domain Controller) which has
its own timer and is in an always on power domain. A specific control
register is provided in RSC address space for this purpose. PDC wakes-up
the RSC and sets up the resources back in active state before the
processor is woken up by a timer interrupt.

Signed-off-by: Raju P.L.S.S.S.N <rplsssn@...eaurora.org>
---
 drivers/soc/qcom/Kconfig  |  2 +-
 drivers/soc/qcom/cpu_pd.c | 79 +++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 80 insertions(+), 1 deletion(-)

diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
index 91e8b3b..9abaeab 100644
--- a/drivers/soc/qcom/Kconfig
+++ b/drivers/soc/qcom/Kconfig
@@ -105,7 +105,7 @@ config QCOM_RPMH
 
 config QCOM_CPU_PD
     bool "Qualcomm cpu power domain driver"
-    depends on QCOM_RPMH && PM_GENERIC_DOMAINS || COMPILE_TEST
+    depends on QCOM_RPMH && PM_GENERIC_DOMAINS && PM_SLEEP || COMPILE_TEST
     help
 	  Support for QCOM platform cpu power management to perform tasks
 	  necessary while application processor votes for deeper modes so that
diff --git a/drivers/soc/qcom/cpu_pd.c b/drivers/soc/qcom/cpu_pd.c
index 565c510..242eced 100644
--- a/drivers/soc/qcom/cpu_pd.c
+++ b/drivers/soc/qcom/cpu_pd.c
@@ -3,19 +3,80 @@
  * Copyright (c) 2018, The Linux Foundation. All rights reserved.
  */
 
+#include <linux/ktime.h>
 #include <linux/of_platform.h>
 #include <linux/pm_domain.h>
 #include <linux/slab.h>
+#include <linux/tick.h>
 
 #include <soc/qcom/rpmh.h>
 
+#define ARCH_TIMER_HZ (19200000)
+#define PDC_TIME_VALID_SHIFT	31
+#define PDC_TIME_UPPER_MASK	0xFFFFFF
 static struct device *cpu_pd_dev;
+static bool suspend;
+
+static uint64_t us_to_ticks(uint64_t time_us)
+{
+	uint64_t sec, nsec, time_cycles;
+
+	sec = time_us;
+	do_div(sec, USEC_PER_SEC);
+	nsec = time_us - sec * USEC_PER_SEC;
+
+	if (nsec > 0) {
+		nsec = nsec * NSEC_PER_USEC;
+		do_div(nsec, NSEC_PER_SEC);
+	}
+
+	sec += nsec;
+
+	time_cycles = (u64)sec * ARCH_TIMER_HZ;
+
+	return time_cycles;
+}
+
+static int setup_pdc_wakeup_timer(struct device *dev)
+{
+	int cpu;
+	struct tcs_cmd cmd[2] = { { 0 } };
+	ktime_t next_wakeup, cpu_wakeup;
+	uint64_t wakeup_cycles = ~0ULL;
+
+	if (!suspend) {
+		/*
+		 * Find the next wakeup for any of the online CPUs
+		 */
+		next_wakeup = ktime_set(KTIME_SEC_MAX, 0);
+		for_each_online_cpu(cpu) {
+			cpu_wakeup = tick_nohz_get_next_wakeup(cpu);
+			if (ktime_before(cpu_wakeup, next_wakeup))
+				next_wakeup = cpu_wakeup;
+		}
+		wakeup_cycles = us_to_ticks(ktime_to_us(next_wakeup));
+	}
+
+	cmd[0].data =  (wakeup_cycles >> 32) & PDC_TIME_UPPER_MASK;
+	cmd[0].data |= 1 << PDC_TIME_VALID_SHIFT;
+	cmd[1].data = (wakeup_cycles & 0xFFFFFFFF);
+
+	return rpmh_write_pdc_data(dev, cmd, ARRAY_SIZE(cmd));
+}
 
 static int cpu_pd_power_off(struct generic_pm_domain *domain)
 {
 	if (rpmh_ctrlr_idle(cpu_pd_dev)) {
 		/* Flush the sleep/wake sets */
 		rpmh_flush(cpu_pd_dev);
+		/*
+		 * The next wakeup value is converted to ticks
+		 * and copied to the Power Domain Controller
+		 * that has its own timer, which is in an
+		 * always-on power domain. The programming is
+		 * done through a separate register on the RSC
+		 */
+		setup_pdc_wakeup_timer(cpu_pd_dev);
 	} else {
 		pr_debug("rpmh controller is busy\n");
 		return -EBUSY;
@@ -89,6 +150,23 @@ static int cpu_pm_domain_probe(struct platform_device *pdev)
 	return ret;
 }
 
+static int cpu_pd_suspend(struct device *dev)
+{
+	suspend = true;
+	return 0;
+}
+
+static int cpu_pd_resume(struct device *dev)
+{
+	suspend = false;
+	return 0;
+}
+
+static const struct dev_pm_ops cpu_pd_dev_pm_ops = {
+	SET_LATE_SYSTEM_SLEEP_PM_OPS(cpu_pd_suspend, cpu_pd_resume)
+};
+
+
 static const struct of_device_id cpu_pd_drv_match[] = {
 	{ .compatible = "qcom,cpu-pm-domain", },
 	{ }
@@ -99,6 +177,7 @@ static int cpu_pm_domain_probe(struct platform_device *pdev)
 	.driver	= {
 		.name = "cpu_pm_domain",
 		.of_match_table = cpu_pd_drv_match,
+		.pm = &cpu_pd_dev_pm_ops,
 	},
 };
 builtin_platform_driver(cpu_pm_domain_driver);
-- 
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