[PATCH RFC 2/5] drivers: qcom: rpmh-pdc-timer: add PDC timer support for RPMH based SoCs

["Raju P.L.S.S.S.N" <rplsssn@codeaurora.org>]

RPMH based targets require that 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. 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@codeaurora.org>
---
 drivers/soc/qcom/Kconfig          |   9 ++
 drivers/soc/qcom/Makefile         |   1 +
 drivers/soc/qcom/rpmh-pdc-timer.c | 181 ++++++++++++++++++++++++++++++
 3 files changed, 191 insertions(+)
 create mode 100644 drivers/soc/qcom/rpmh-pdc-timer.c

diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
index 684cb51694d1..d04724ea5490 100644
--- a/drivers/soc/qcom/Kconfig
+++ b/drivers/soc/qcom/Kconfig
@@ -103,6 +103,15 @@ config QCOM_RPMH
 	  of hardware components aggregate requests for these resources and
 	  help apply the aggregated state on the resource.
 
+config QCOM_RPMH_PDC_TIMER
+	bool "Qualcomm PDC Timer for RPM-Hardened based SoCs"
+	depends on CPU_PM
+	help
+	  Support for QCOM platform next wakeup timer programming when
+	  application processor enters SoC level deepest low power mode.
+	  The wakeup is programmed to PDC (Power Domain Controller)
+	  timer which is in always on power domain.
+
 config QCOM_SMEM
 	tristate "Qualcomm Shared Memory Manager (SMEM)"
 	depends on ARCH_QCOM || COMPILE_TEST
diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
index f25b54cd6cf8..2ddb7e4f9098 100644
--- a/drivers/soc/qcom/Makefile
+++ b/drivers/soc/qcom/Makefile
@@ -12,6 +12,7 @@ obj-$(CONFIG_QCOM_RMTFS_MEM)	+= rmtfs_mem.o
 obj-$(CONFIG_QCOM_RPMH)		+= qcom_rpmh.o
 qcom_rpmh-y			+= rpmh-rsc.o
 qcom_rpmh-y			+= rpmh.o
+obj-$(CONFIG_QCOM_RPMH_PDC_TIMER) += rpmh-pdc-timer.o
 obj-$(CONFIG_QCOM_SMD_RPM)	+= smd-rpm.o
 obj-$(CONFIG_QCOM_SMEM) +=	smem.o
 obj-$(CONFIG_QCOM_SMEM_STATE) += smem_state.o
diff --git a/drivers/soc/qcom/rpmh-pdc-timer.c b/drivers/soc/qcom/rpmh-pdc-timer.c
new file mode 100644
index 000000000000..108ea4a2df89
--- /dev/null
+++ b/drivers/soc/qcom/rpmh-pdc-timer.c
@@ -0,0 +1,181 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/cpu_pm.h>
+#include <linux/kernel.h>
+#include <linux/ktime.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+#include <linux/tick.h>
+#include <asm/arch_timer.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 regmap *rsc_regmap;
+static resource_size_t cmd0_data_offset;
+static resource_size_t cmd1_data_offset;
+static uint64_t pdc_wakeup = ~0ULL;
+static raw_spinlock_t pdc_wakeup_lock;
+
+/* convert micro sec to ticks or clock cycles
+ *
+ *   time in cycles = (time in sec) * Freq
+ *                  = (time in sec) * 19200000
+ *
+ * However, while converting micro sec to sec,
+ * there is a possibility of round of errors.
+ * So round of errors are minimized by finding
+ * nano sec.
+ */
+static uint64_t us_to_cycles(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;
+}
+
+/*
+ * Find next wakeup of a cpu and convert into
+ * cycles.
+ */
+static uint64_t get_next_wakeup_cycles(int cpu)
+{
+	ktime_t next_wakeup;
+	uint64_t next_wakeup_cycles;
+
+	next_wakeup = tick_nohz_get_next_wakeup(cpu);
+
+	/*
+	 * Find the relative wakeup from current time
+	 * in kernel time scale
+	 */
+	next_wakeup = ktime_sub(next_wakeup, ktime_get());
+
+	next_wakeup_cycles = us_to_cycles(ktime_to_us(next_wakeup));
+
+	/*
+	 * Add current time in arch timer scale.
+	 * This is needed as PDC match value is programmed
+	 * with absolute value, not the relative value
+	 * from current time
+	 */
+	next_wakeup_cycles += arch_counter_get_cntvct();
+
+	return next_wakeup_cycles;
+}
+
+static void setup_pdc_wakeup_timer(uint64_t wakeup_cycles)
+{
+	u32 data0, data1;
+
+	data0 =  (wakeup_cycles >> 32) & PDC_TIME_UPPER_MASK;
+	data0 |= 1 << PDC_TIME_VALID_SHIFT;
+	data1 = (wakeup_cycles & 0xFFFFFFFF);
+
+	regmap_write(rsc_regmap, cmd0_data_offset, data0);
+	regmap_write(rsc_regmap, cmd1_data_offset, data1);
+
+}
+
+static int cpu_pm_notifier(struct notifier_block *b,
+			       unsigned long cmd, void *v)
+{
+	uint64_t cpu_next_wakeup;
+
+	switch (cmd) {
+	case CPU_PM_ENTER:
+		cpu_next_wakeup = get_next_wakeup_cycles(smp_processor_id());
+		raw_spin_lock(&pdc_wakeup_lock);
+		/*
+		 * If PDC wakeup is expired or
+		 * If current cpu next wakeup is early,
+		 * program the same to pdc wakeup
+		 */
+		if ((pdc_wakeup < arch_counter_get_cntvct()) ||
+				(cpu_next_wakeup < pdc_wakeup)) {
+			pdc_wakeup = cpu_next_wakeup;
+			setup_pdc_wakeup_timer(pdc_wakeup);
+		}
+		raw_spin_unlock(&pdc_wakeup_lock);
+		break;
+	default:
+		return NOTIFY_DONE;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block cpu_pm_notifier_block = {
+	.notifier_call = cpu_pm_notifier,
+	.priority = -1, /* Should be last in the order of notifications */
+};
+
+static int pdc_timer_probe(struct platform_device *pdev)
+{
+	struct device *pdc_timer_dev = &pdev->dev;
+	struct resource *res = NULL;
+
+	if (IS_ERR_OR_NULL(pdc_timer_dev)) {
+		pr_err("%s fail\n", __func__);
+		return PTR_ERR(pdc_timer_dev);
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res) {
+		pr_err("res not found\n");
+		return -ENODEV;
+	}
+	cmd0_data_offset = res->start;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
+	if (!res) {
+		pr_err("res not found\n");
+		return -ENODEV;
+	}
+	cmd1_data_offset =  res->start;
+
+	rsc_regmap = dev_get_regmap(pdc_timer_dev->parent, NULL);
+	if (!rsc_regmap) {
+		pr_err("regmap for parent is not found\n");
+		return -ENODEV;
+	}
+
+	raw_spin_lock_init(&pdc_wakeup_lock);
+	cpu_pm_register_notifier(&cpu_pm_notifier_block);
+
+	return 0;
+}
+
+static const struct of_device_id pdc_timer_drv_match[] = {
+	{ .compatible = "qcom,pdc-timer", },
+	{ }
+};
+
+static struct platform_driver pdc_timer_driver = {
+	.probe = pdc_timer_probe,
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.of_match_table = pdc_timer_drv_match,
+	},
+};
+builtin_platform_driver(pdc_timer_driver);
-- 
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