[PATCH 4/7] coresight: etm4x: Change etm4_platform_driver driver for MMIO devices

[Anshuman Khandual]

This updates existing etm4_platform_driver to accommodate MMIO based device
tree represented coresight etm4x devices along with current sysreg ones. It
first looks for 'apb_clk' clock and tries to enable it via a new helper i.e
coresight_get_enable_apb_pclk(). If 'apb_clock' is not found on the system
as indicated by a return value 'NULL', ignore and proceed further assuming
that platform already has got required clocks enabled. But if the clock is
but could not be enabled, device probe fails with -ENODEV. Similarly iomem
base address is fetched via devm_ioremap_resource() onyl when the platform
has valid 'struct resource'. The probed device is ensured to be a coresight
etm4x, via two new helpers in etm4_init_iomem_access(). This also registers
runtime power management callbacks i.e for suspend and resume operations.

Cc: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
Cc: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
Cc: Mike Leach <mike.leach@xxxxxxxxxx>
Cc: Leo Yan <leo.yan@xxxxxxxxxx>
Cc: coresight@xxxxxxxxxxxxxxxx
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Signed-off-by: Anshuman Khandual <anshuman.khandual@xxxxxxx>
---
 .../coresight/coresight-etm4x-core.c          | 62 +++++++++++++++++--
 drivers/hwtracing/coresight/coresight-etm4x.h |  3 +
 include/linux/coresight.h                     | 44 +++++++++++++
 3 files changed, 105 insertions(+), 4 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etm4x-core.c b/drivers/hwtracing/coresight/coresight-etm4x-core.c
index a4c138e67920..60f027e33aa0 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x-core.c
+++ b/drivers/hwtracing/coresight/coresight-etm4x-core.c
@@ -30,6 +30,7 @@
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
 #include <linux/property.h>
+#include <linux/clk/clk-conf.h>
 
 #include <asm/barrier.h>
 #include <asm/sections.h>
@@ -1067,12 +1068,24 @@ static bool etm4_init_sysreg_access(struct etmv4_drvdata *drvdata,
 	return true;
 }
 
+static bool is_etm4x_device(void __iomem *base)
+{
+	u32 devarch = readl(base + TRCDEVARCH);
+	u32 devtype = readl(base + TRCDEVTYPE);
+
+	return (((devarch & ETM_DEVARCH_ID_MASK) == ETM_DEVARCH_ETMv4x_ARCH) &&
+		(devtype == ETM_DEVTYPE_ETMv4x_ARCH));
+}
+
 static bool etm4_init_iomem_access(struct etmv4_drvdata *drvdata,
 				   struct csdev_access *csa)
 {
 	u32 devarch = readl_relaxed(drvdata->base + TRCDEVARCH);
 	u32 idr1 = readl_relaxed(drvdata->base + TRCIDR1);
 
+	if (!is_coresight_device(drvdata->base) || !is_etm4x_device(drvdata->base))
+		return false;
+
 	/*
 	 * All ETMs must implement TRCDEVARCH to indicate that
 	 * the component is an ETMv4. To support any broken
@@ -2133,6 +2146,7 @@ static int etm4_probe_amba(struct amba_device *adev, const struct amba_id *id)
 
 static int etm4_probe_platform_dev(struct platform_device *pdev)
 {
+	struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	struct etmv4_drvdata *drvdata;
 	int ret;
 
@@ -2140,7 +2154,16 @@ static int etm4_probe_platform_dev(struct platform_device *pdev)
 	if (!drvdata)
 		return -ENOMEM;
 
-	drvdata->base = NULL;
+	drvdata->pclk = coresight_get_enable_apb_pclk(&pdev->dev);
+	if (IS_ERR(drvdata->pclk))
+		return -ENODEV;
+
+	if (res) {
+		drvdata->base = devm_ioremap_resource(&pdev->dev, res);
+		if (IS_ERR(drvdata->base))
+			return PTR_ERR(drvdata->base);
+	}
+
 	dev_set_drvdata(&pdev->dev, drvdata);
 	pm_runtime_get_noresume(&pdev->dev);
 	pm_runtime_set_active(&pdev->dev);
@@ -2186,7 +2209,7 @@ static struct amba_cs_uci_id uci_id_etm4[] = {
 		/*  ETMv4 UCI data */
 		.devarch	= ETM_DEVARCH_ETMv4x_ARCH,
 		.devarch_mask	= ETM_DEVARCH_ID_MASK,
-		.devtype	= 0x00000013,
+		.devtype	= ETM_DEVTYPE_ETMv4x_ARCH,
 	}
 };
 
@@ -2244,6 +2267,10 @@ static int __exit etm4_remove_platform_dev(struct platform_device *pdev)
 
 	if (drvdata)
 		ret = etm4_remove_dev(drvdata);
+
+	if (!IS_ERR(drvdata->pclk))
+		clk_put(drvdata->pclk);
+
 	pm_runtime_disable(&pdev->dev);
 	return ret;
 }
@@ -2284,7 +2311,34 @@ static struct amba_driver etm4x_amba_driver = {
 	.id_table	= etm4_ids,
 };
 
-static const struct of_device_id etm4_sysreg_match[] = {
+#ifdef CONFIG_PM
+static int etm4_runtime_suspend(struct device *dev)
+{
+	struct etmv4_drvdata *drvdata = dev_get_drvdata(dev);
+
+	if (!IS_ERR(drvdata->pclk))
+		clk_disable_unprepare(drvdata->pclk);
+
+	return 0;
+}
+
+static int etm4_runtime_resume(struct device *dev)
+{
+	struct etmv4_drvdata *drvdata = dev_get_drvdata(dev);
+
+	if (!IS_ERR(drvdata->pclk))
+		clk_prepare_enable(drvdata->pclk);
+
+	return 0;
+}
+#endif
+
+static const struct dev_pm_ops etm4_dev_pm_ops = {
+	SET_RUNTIME_PM_OPS(etm4_runtime_suspend, etm4_runtime_resume, NULL)
+};
+
+static const struct of_device_id etm4_match[] = {
+	{ .compatible	= "arm,coresight-etm4x" },
 	{ .compatible	= "arm,coresight-etm4x-sysreg" },
 	{ .compatible	= "arm,embedded-trace-extension" },
 	{}
@@ -2295,7 +2349,7 @@ static struct platform_driver etm4_platform_driver = {
 	.remove		= etm4_remove_platform_dev,
 	.driver			= {
 		.name			= "coresight-etm4x",
-		.of_match_table		= etm4_sysreg_match,
+		.of_match_table		= etm4_match,
 		.suppress_bind_attrs	= true,
 	},
 };
diff --git a/drivers/hwtracing/coresight/coresight-etm4x.h b/drivers/hwtracing/coresight/coresight-etm4x.h
index 434f4e95ee17..5a37df4a02e9 100644
--- a/drivers/hwtracing/coresight/coresight-etm4x.h
+++ b/drivers/hwtracing/coresight/coresight-etm4x.h
@@ -701,6 +701,8 @@
 #define ETM_DEVARCH_ETE_ARCH						\
 	(ETM_DEVARCH_ARCHITECT_ARM | ETM_DEVARCH_ARCHID_ETE | ETM_DEVARCH_PRESENT)
 
+#define ETM_DEVTYPE_ETMv4x_ARCH		0x00000013
+
 #define TRCSTATR_IDLE_BIT		0
 #define TRCSTATR_PMSTABLE_BIT		1
 #define ETM_DEFAULT_ADDR_COMP		0
@@ -1017,6 +1019,7 @@ struct etmv4_save_state {
  * @arch_features: Bitmap of arch features of etmv4 devices.
  */
 struct etmv4_drvdata {
+	struct clk			*pclk;
 	void __iomem			*base;
 	struct coresight_device		*csdev;
 	spinlock_t			spinlock;
diff --git a/include/linux/coresight.h b/include/linux/coresight.h
index f85b041ea475..75a7aa6d7444 100644
--- a/include/linux/coresight.h
+++ b/include/linux/coresight.h
@@ -6,6 +6,8 @@
 #ifndef _LINUX_CORESIGHT_H
 #define _LINUX_CORESIGHT_H
 
+#include <linux/amba/bus.h>
+#include <linux/clk.h>
 #include <linux/device.h>
 #include <linux/io.h>
 #include <linux/perf_event.h>
@@ -370,6 +372,48 @@ static inline u32 csdev_access_relaxed_read32(struct csdev_access *csa,
 	return csa->read(offset, true, false);
 }
 
+#define CORESIGHT_CIDRn(i)	(0xFF0 + ((i) * 4))
+
+static inline u32 coresight_get_cid(void __iomem *base)
+{
+	u32 i, cid = 0;
+
+	for (i = 0; i < 4; i++)
+		cid |= readl(base + CORESIGHT_CIDRn(i)) << (i * 8);
+
+	return cid;
+}
+
+static inline bool is_coresight_device(void __iomem *base)
+{
+	u32 cid = coresight_get_cid(base);
+
+	return cid == CORESIGHT_CID;
+}
+
+/*
+ * This function attempts to find a 'apb_pclk' clock on the system and
+ * if found, enables it. This returns NULL if 'apb_pclk' clock is not
+ * and return error pointer from clk_prepare_enable(), if it fails to
+ * enable the discovered clock.
+ */
+static inline struct clk *coresight_get_enable_apb_pclk(struct device *dev)
+{
+	struct clk *pclk;
+	int ret;
+
+	pclk = clk_get(dev, "apb_pclk");
+	if (IS_ERR(pclk))
+		return NULL;
+
+	ret = clk_prepare_enable(pclk);
+	if (ret) {
+		clk_put(pclk);
+		return ERR_PTR(ret);
+	}
+	return pclk;
+}
+
 #define CORESIGHT_PIDRn(i)	(0xFE0 + ((i) * 4))
 
 static inline u32 coresight_get_pid(struct csdev_access *csa)
-- 
2.25.1