linux-kernel - [PATCH RFC 4/6] drivers: qcom: system_pm: program next wakeup to PDC timer

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Message-Id: <1535141188-29731-5-git-send-email-rplsssn@codeaurora.org>
Date:   Sat, 25 Aug 2018 01:36:26 +0530
From:   "Raju P.L.S.S.S.N" <rplsssn@...eaurora.org>
To:     andy.gross@...aro.org, david.brown@...aro.org,
        linux-arm-msm@...r.kernel.org, linux-soc@...r.kernel.org,
        linux-pm@...r.kernel.org
Cc:     rnayak@...eaurora.org, bjorn.andersson@...aro.org,
        linux-kernel@...r.kernel.org, lorenzo.pieralisi@....com,
        rafael@...nel.org, drake@...lessm.com, 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 4/6] drivers: qcom: system_pm: 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/system_pm.c | 61 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 61 insertions(+)

diff --git a/drivers/soc/qcom/system_pm.c b/drivers/soc/qcom/system_pm.c
index 8810b84..1451bf8 100644
--- a/drivers/soc/qcom/system_pm.c
+++ b/drivers/soc/qcom/system_pm.c
@@ -5,15 +5,67 @@
 
 #include <linux/cpu_pm.h>
 #include <linux/kernel.h>
+#include <linux/ktime.h>
 #include <linux/platform_device.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 cpumask cpu_pm_state_mask;
 static raw_spinlock_t cpu_pm_state_lock;
 
 static struct device *sys_pm_dev;
 
+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(bool suspend)
+{
+	int cpu;
+	struct tcs_cmd cmd[2] = { { 0 } };
+	ktime_t next_wakeup, cpu_wakeup;
+	uint64_t wakeup_cycles = ~0U;
+
+	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(sys_pm_dev, cmd, ARRAY_SIZE(cmd));
+}
+
 static int sys_pm_notifier(struct notifier_block *b,
 			       unsigned long cmd, void *v)
 {
@@ -25,6 +77,14 @@ static int sys_pm_notifier(struct notifier_block *b,
 			if (rpmh_ctrlr_idle(sys_pm_dev)) {
 				/* Flush the sleep/wake sets */
 				rpmh_flush(sys_pm_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(false);
 			} else {
 				pr_err("%s:rpmh controller is busy\n",
 						__func__);
@@ -72,6 +132,7 @@ static int sys_pm_suspend(struct device *dev)
 	if (rpmh_ctrlr_idle(dev)) {
 		/* Flush the sleep/wake sets in RSC controller */
 		rpmh_flush(dev);
+		setup_pdc_wakeup_timer(true);
 	} else {
 		pr_err("%s:rpmh controller is busy\n", __func__);
 		return -EBUSY;
-- 
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