Merge tag 'samsung-drivers-6.18' of https://git.kernel.org/pub/scm/linux/kernel/git/krzk/linux into soc/drivers

Samsung SoC drivers for v6.18

1. Google GS101:
   Enable CPU Idle, which needs programming C2 idle hints
   via ACPM firmware (Alive Clock and Power Manager).  The patch
   introducing this depends on 'local-timer-stop' Devicetree property,
   which was merged in v6.17.

   Fix handling error codes in ACPM firmware driver when talking to
   PMIC.

2. Exynos2200: Add dedicated compatible for serial engines (USI).

* tag 'samsung-drivers-6.18' of https://git.kernel.org/pub/scm/linux/kernel/git/krzk/linux:
  firmware: exynos-acpm: fix PMIC returned errno
  dt-bindings: soc: samsung: usi: add samsung,exynos2200-usi compatible
  soc: samsung: exynos-pmu: Enable CPU Idle for gs101

Link: https://lore.kernel.org/r/20250912135448.203678-2-krzysztof.kozlowski@linaro.org
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

3 files changed, 275 insertions, 27 deletions

diff --git a/Documentation/devicetree/bindings/soc/samsung/exynos-usi.yaml b/Documentation/devicetree/bindings/soc/samsung/exynos-usi.yaml
index cb22637091e8..c694926e56ef 100644
--- a/Documentation/devicetree/bindings/soc/samsung/exynos-usi.yaml
+++ b/Documentation/devicetree/bindings/soc/samsung/exynos-usi.yaml
@@ -36,6 +36,7 @@ properties:
       - items:
           - enum:
               - google,gs101-usi
+              - samsung,exynos2200-usi
               - samsung,exynosautov9-usi
               - samsung,exynosautov920-usi
           - const: samsung,exynos850-usi
diff --git a/drivers/firmware/samsung/exynos-acpm-pmic.c b/drivers/firmware/samsung/exynos-acpm-pmic.c
index 39b33a356ebd..961d7599e422 100644
--- a/drivers/firmware/samsung/exynos-acpm-pmic.c
+++ b/drivers/firmware/samsung/exynos-acpm-pmic.c
@@ -4,7 +4,9 @@
  * Copyright 2020 Google LLC.
  * Copyright 2024 Linaro Ltd.
  */
+#include <linux/array_size.h>
 #include <linux/bitfield.h>
+#include <linux/errno.h>
 #include <linux/firmware/samsung/exynos-acpm-protocol.h>
 #include <linux/ktime.h>
 #include <linux/types.h>
@@ -33,6 +35,19 @@ enum exynos_acpm_pmic_func {
 	ACPM_PMIC_BULK_WRITE,
 };
 
+static const int acpm_pmic_linux_errmap[] = {
+	[0] = 0, /* ACPM_PMIC_SUCCESS */
+	[1] = -EACCES, /* Read register can't be accessed or issues to access it. */
+	[2] = -EACCES, /* Write register can't be accessed or issues to access it. */
+};
+
+static int acpm_pmic_to_linux_err(int err)
+{
+	if (err >= 0 && err < ARRAY_SIZE(acpm_pmic_linux_errmap))
+		return acpm_pmic_linux_errmap[err];
+	return -EIO;
+}
+
 static inline u32 acpm_pmic_set_bulk(u32 data, unsigned int i)
 {
 	return (data & ACPM_PMIC_BULK_MASK) << (ACPM_PMIC_BULK_SHIFT * i);
@@ -79,7 +94,7 @@ int acpm_pmic_read_reg(const struct acpm_handle *handle,
 
 	*buf = FIELD_GET(ACPM_PMIC_VALUE, xfer.rxd[1]);
 
-	return FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]);
+	return acpm_pmic_to_linux_err(FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]));
 }
 
 static void acpm_pmic_init_bulk_read_cmd(u32 cmd[4], u8 type, u8 reg, u8 chan,
@@ -110,7 +125,7 @@ int acpm_pmic_bulk_read(const struct acpm_handle *handle,
 	if (ret)
 		return ret;
 
-	ret = FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]);
+	ret = acpm_pmic_to_linux_err(FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]));
 	if (ret)
 		return ret;
 
@@ -150,7 +165,7 @@ int acpm_pmic_write_reg(const struct acpm_handle *handle,
 	if (ret)
 		return ret;
 
-	return FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]);
+	return acpm_pmic_to_linux_err(FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]));
 }
 
 static void acpm_pmic_init_bulk_write_cmd(u32 cmd[4], u8 type, u8 reg, u8 chan,
@@ -190,7 +205,7 @@ int acpm_pmic_bulk_write(const struct acpm_handle *handle,
 	if (ret)
 		return ret;
 
-	return FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]);
+	return acpm_pmic_to_linux_err(FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]));
 }
 
 static void acpm_pmic_init_update_cmd(u32 cmd[4], u8 type, u8 reg, u8 chan,
@@ -220,5 +235,5 @@ int acpm_pmic_update_reg(const struct acpm_handle *handle,
 	if (ret)
 		return ret;
 
-	return FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]);
+	return acpm_pmic_to_linux_err(FIELD_GET(ACPM_PMIC_RETURN, xfer.rxd[1]));
 }
diff --git a/drivers/soc/samsung/exynos-pmu.c b/drivers/soc/samsung/exynos-pmu.c
index a77288f49d24..22c50ca2aa79 100644
--- a/drivers/soc/samsung/exynos-pmu.c
+++ b/drivers/soc/samsung/exynos-pmu.c
@@ -7,7 +7,9 @@
 
 #include <linux/array_size.h>
 #include <linux/arm-smccc.h>
+#include <linux/bitmap.h>
 #include <linux/cpuhotplug.h>
+#include <linux/cpu_pm.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
 #include <linux/mfd/core.h>
@@ -15,6 +17,7 @@
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/delay.h>
+#include <linux/reboot.h>
 #include <linux/regmap.h>
 
 #include <linux/soc/samsung/exynos-regs-pmu.h>
@@ -35,6 +38,15 @@ struct exynos_pmu_context {
 	const struct exynos_pmu_data *pmu_data;
 	struct regmap *pmureg;
 	struct regmap *pmuintrgen;
+	/*
+	 * Serialization lock for CPU hot plug and cpuidle ACPM hint
+	 * programming. Also protects in_cpuhp, sys_insuspend & sys_inreboot
+	 * flags.
+	 */
+	raw_spinlock_t cpupm_lock;
+	unsigned long *in_cpuhp;
+	bool sys_insuspend;
+	bool sys_inreboot;
 };
 
 void __iomem *pmu_base_addr;
@@ -221,6 +233,15 @@ static const struct regmap_config regmap_smccfg = {
 	.reg_read = tensor_sec_reg_read,
 	.reg_write = tensor_sec_reg_write,
 	.reg_update_bits = tensor_sec_update_bits,
+	.use_raw_spinlock = true,
+};
+
+static const struct regmap_config regmap_pmu_intr = {
+	.name = "pmu_intr_gen",
+	.reg_bits = 32,
+	.reg_stride = 4,
+	.val_bits = 32,
+	.use_raw_spinlock = true,
 };
 
 static const struct exynos_pmu_data gs101_pmu_data = {
@@ -330,13 +351,19 @@ struct regmap *exynos_get_pmu_regmap_by_phandle(struct device_node *np,
 EXPORT_SYMBOL_GPL(exynos_get_pmu_regmap_by_phandle);
 
 /*
- * CPU_INFORM register hint values which are used by
- * EL3 firmware (el3mon).
+ * CPU_INFORM register "hint" values are required to be programmed in addition to
+ * the standard PSCI calls to have functional CPU hotplug and CPU idle states.
+ * This is required to workaround limitations in the el3mon/ACPM firmware.
  */
 #define CPU_INFORM_CLEAR	0
 #define CPU_INFORM_C2		1
 
-static int gs101_cpuhp_pmu_online(unsigned int cpu)
+/*
+ * __gs101_cpu_pmu_ prefix functions are common code shared by CPU PM notifiers
+ * (CPUIdle) and CPU hotplug callbacks. Functions should be called with IRQs
+ * disabled and cpupm_lock held.
+ */
+static int __gs101_cpu_pmu_online(unsigned int cpu)
 {
 	unsigned int cpuhint = smp_processor_id();
 	u32 reg, mask;
@@ -358,10 +385,48 @@ static int gs101_cpuhp_pmu_online(unsigned int cpu)
 	return 0;
 }
 
-static int gs101_cpuhp_pmu_offline(unsigned int cpu)
+/* Called from CPU PM notifier (CPUIdle code path) with IRQs disabled */
+static int gs101_cpu_pmu_online(void)
+{
+	int cpu;
+
+	raw_spin_lock(&pmu_context->cpupm_lock);
+
+	if (pmu_context->sys_inreboot) {
+		raw_spin_unlock(&pmu_context->cpupm_lock);
+		return NOTIFY_OK;
+	}
+
+	cpu = smp_processor_id();
+	__gs101_cpu_pmu_online(cpu);
+	raw_spin_unlock(&pmu_context->cpupm_lock);
+
+	return NOTIFY_OK;
+}
+
+/* Called from CPU hot plug callback with IRQs enabled */
+static int gs101_cpuhp_pmu_online(unsigned int cpu)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&pmu_context->cpupm_lock, flags);
+
+	__gs101_cpu_pmu_online(cpu);
+	/*
+	 * Mark this CPU as having finished the hotplug.
+	 * This means this CPU can now enter C2 idle state.
+	 */
+	clear_bit(cpu, pmu_context->in_cpuhp);
+	raw_spin_unlock_irqrestore(&pmu_context->cpupm_lock, flags);
+
+	return 0;
+}
+
+/* Common function shared by both CPU hot plug and CPUIdle */
+static int __gs101_cpu_pmu_offline(unsigned int cpu)
 {
-	u32 reg, mask;
 	unsigned int cpuhint = smp_processor_id();
+	u32 reg, mask;
 
 	/* set cpu inform hint */
 	regmap_write(pmu_context->pmureg, GS101_CPU_INFORM(cpuhint),
@@ -379,6 +444,165 @@ static int gs101_cpuhp_pmu_offline(unsigned int cpu)
 	regmap_read(pmu_context->pmuintrgen, GS101_GRP1_INTR_BID_UPEND, &reg);
 	regmap_write(pmu_context->pmuintrgen, GS101_GRP1_INTR_BID_CLEAR,
 		     reg & mask);
+
+	return 0;
+}
+
+/* Called from CPU PM notifier (CPUIdle code path) with IRQs disabled */
+static int gs101_cpu_pmu_offline(void)
+{
+	int cpu;
+
+	raw_spin_lock(&pmu_context->cpupm_lock);
+	cpu = smp_processor_id();
+
+	if (test_bit(cpu, pmu_context->in_cpuhp)) {
+		raw_spin_unlock(&pmu_context->cpupm_lock);
+		return NOTIFY_BAD;
+	}
+
+	/* Ignore CPU_PM_ENTER event in reboot or suspend sequence. */
+	if (pmu_context->sys_insuspend || pmu_context->sys_inreboot) {
+		raw_spin_unlock(&pmu_context->cpupm_lock);
+		return NOTIFY_OK;
+	}
+
+	__gs101_cpu_pmu_offline(cpu);
+	raw_spin_unlock(&pmu_context->cpupm_lock);
+
+	return NOTIFY_OK;
+}
+
+/* Called from CPU hot plug callback with IRQs enabled */
+static int gs101_cpuhp_pmu_offline(unsigned int cpu)
+{
+	unsigned long flags;
+
+	raw_spin_lock_irqsave(&pmu_context->cpupm_lock, flags);
+	/*
+	 * Mark this CPU as entering hotplug. So as not to confuse
+	 * ACPM the CPU entering hotplug should not enter C2 idle state.
+	 */
+	set_bit(cpu, pmu_context->in_cpuhp);
+	__gs101_cpu_pmu_offline(cpu);
+
+	raw_spin_unlock_irqrestore(&pmu_context->cpupm_lock, flags);
+
+	return 0;
+}
+
+static int gs101_cpu_pm_notify_callback(struct notifier_block *self,
+					unsigned long action, void *v)
+{
+	switch (action) {
+	case CPU_PM_ENTER:
+		return gs101_cpu_pmu_offline();
+
+	case CPU_PM_EXIT:
+		return gs101_cpu_pmu_online();
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block gs101_cpu_pm_notifier = {
+	.notifier_call = gs101_cpu_pm_notify_callback,
+	/*
+	 * We want to be called first, as the ACPM hint and handshake is what
+	 * puts the CPU into C2.
+	 */
+	.priority = INT_MAX
+};
+
+static int exynos_cpupm_reboot_notifier(struct notifier_block *nb,
+					unsigned long event, void *v)
+{
+	unsigned long flags;
+
+	switch (event) {
+	case SYS_POWER_OFF:
+	case SYS_RESTART:
+		raw_spin_lock_irqsave(&pmu_context->cpupm_lock, flags);
+		pmu_context->sys_inreboot = true;
+		raw_spin_unlock_irqrestore(&pmu_context->cpupm_lock, flags);
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block exynos_cpupm_reboot_nb = {
+	.priority = INT_MAX,
+	.notifier_call = exynos_cpupm_reboot_notifier,
+};
+
+static int setup_cpuhp_and_cpuidle(struct device *dev)
+{
+	struct device_node *intr_gen_node;
+	struct resource intrgen_res;
+	void __iomem *virt_addr;
+	int ret, cpu;
+
+	intr_gen_node = of_parse_phandle(dev->of_node,
+					 "google,pmu-intr-gen-syscon", 0);
+	if (!intr_gen_node) {
+		/*
+		 * To maintain support for older DTs that didn't specify syscon
+		 * phandle just issue a warning rather than fail to probe.
+		 */
+		dev_warn(dev, "pmu-intr-gen syscon unavailable\n");
+		return 0;
+	}
+
+	/*
+	 * To avoid lockdep issues (CPU PM notifiers use raw spinlocks) create
+	 * a mmio regmap for pmu-intr-gen that uses raw spinlocks instead of
+	 * syscon provided regmap.
+	 */
+	ret = of_address_to_resource(intr_gen_node, 0, &intrgen_res);
+	of_node_put(intr_gen_node);
+
+	virt_addr = devm_ioremap(dev, intrgen_res.start,
+				 resource_size(&intrgen_res));
+	if (!virt_addr)
+		return -ENOMEM;
+
+	pmu_context->pmuintrgen = devm_regmap_init_mmio(dev, virt_addr,
+							&regmap_pmu_intr);
+	if (IS_ERR(pmu_context->pmuintrgen)) {
+		dev_err(dev, "failed to initialize pmu-intr-gen regmap\n");
+		return PTR_ERR(pmu_context->pmuintrgen);
+	}
+
+	/* register custom mmio regmap with syscon */
+	ret = of_syscon_register_regmap(intr_gen_node,
+					pmu_context->pmuintrgen);
+	if (ret)
+		return ret;
+
+	pmu_context->in_cpuhp = devm_bitmap_zalloc(dev, num_possible_cpus(),
+						   GFP_KERNEL);
+	if (!pmu_context->in_cpuhp)
+		return -ENOMEM;
+
+	raw_spin_lock_init(&pmu_context->cpupm_lock);
+	pmu_context->sys_inreboot = false;
+	pmu_context->sys_insuspend = false;
+
+	/* set PMU to power on */
+	for_each_online_cpu(cpu)
+		gs101_cpuhp_pmu_online(cpu);
+
+	/* register CPU hotplug callbacks */
+	cpuhp_setup_state(CPUHP_BP_PREPARE_DYN,	"soc/exynos-pmu:prepare",
+			  gs101_cpuhp_pmu_online, NULL);
+
+	cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "soc/exynos-pmu:online",
+			  NULL, gs101_cpuhp_pmu_offline);
+
+	/* register CPU PM notifiers for cpuidle */
+	cpu_pm_register_notifier(&gs101_cpu_pm_notifier);
+	register_reboot_notifier(&exynos_cpupm_reboot_nb);
 	return 0;
 }
 
@@ -435,23 +659,9 @@ static int exynos_pmu_probe(struct platform_device *pdev)
 	pmu_context->dev = dev;
 
 	if (pmu_context->pmu_data && pmu_context->pmu_data->pmu_cpuhp) {
-		pmu_context->pmuintrgen = syscon_regmap_lookup_by_phandle(dev->of_node,
-							"google,pmu-intr-gen-syscon");
-		if (IS_ERR(pmu_context->pmuintrgen)) {
-			/*
-			 * To maintain support for older DTs that didn't specify syscon phandle
-			 * just issue a warning rather than fail to probe.
-			 */
-			dev_warn(&pdev->dev, "pmu-intr-gen syscon unavailable\n");
-		} else {
-			cpuhp_setup_state(CPUHP_BP_PREPARE_DYN,
-					  "soc/exynos-pmu:prepare",
-					  gs101_cpuhp_pmu_online, NULL);
-
-			cpuhp_setup_state(CPUHP_AP_ONLINE_DYN,
-					  "soc/exynos-pmu:online",
-					  NULL, gs101_cpuhp_pmu_offline);
-		}
+		ret = setup_cpuhp_and_cpuidle(dev);
+		if (ret)
+			return ret;
 	}
 
 	if (pmu_context->pmu_data && pmu_context->pmu_data->pmu_init)
@@ -471,10 +681,32 @@ static int exynos_pmu_probe(struct platform_device *pdev)
 	return 0;
 }
 
+static int exynos_cpupm_suspend_noirq(struct device *dev)
+{
+	raw_spin_lock(&pmu_context->cpupm_lock);
+	pmu_context->sys_insuspend = true;
+	raw_spin_unlock(&pmu_context->cpupm_lock);
+	return 0;
+}
+
+static int exynos_cpupm_resume_noirq(struct device *dev)
+{
+	raw_spin_lock(&pmu_context->cpupm_lock);
+	pmu_context->sys_insuspend = false;
+	raw_spin_unlock(&pmu_context->cpupm_lock);
+	return 0;
+}
+
+static const struct dev_pm_ops cpupm_pm_ops = {
+	NOIRQ_SYSTEM_SLEEP_PM_OPS(exynos_cpupm_suspend_noirq,
+				  exynos_cpupm_resume_noirq)
+};
+
 static struct platform_driver exynos_pmu_driver = {
 	.driver  = {
 		.name   = "exynos-pmu",
 		.of_match_table = exynos_pmu_of_device_ids,
+		.pm = pm_sleep_ptr(&cpupm_pm_ops),
 	},
 	.probe = exynos_pmu_probe,
 };