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

Anshuman Khandual
2023-03-17T03:06:29Z

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@linaro.org>
Cc: Suzuki K Poulose <suzuki.poulose@arm.com>
Cc: Mike Leach <mike.leach@linaro.org>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: coresight@lists.linaro.org
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
---
.../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