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[PATCH v6 00/12] arm-cci: PMU driver updates

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  [PATCH v6 00/12] arm-cci: PMU driver updates "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2016-01-25 12:30 +0100
    [PATCH v6 03/12] arm-cci: Refactor CCI PMU enable/disable methods "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2016-01-25 12:30 +0100
    [PATCH v6 11/12] arm-cci500: Rearrange PMU driver for code sharing with CCI-550 PMU "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2016-01-25 12:30 +0100
    [PATCH v6 05/12] arm-cci: write_counter: Remove redundant check "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2016-01-25 12:30 +0100
    [PATCH v6 01/12] arm-cci: simplify sysfs attr handling "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2016-01-25 12:30 +0100
    [PATCH v6 06/12] arm-cci: Get the status of a counter "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2016-01-25 12:30 +0100
    [PATCH v6 07/12] arm-cci: Add routines to save/restore all counters "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2016-01-25 12:30 +0100
    [PATCH v6 10/12] arm-cci: CCI-500: Work around PMU counter writes "Suzuki K. Poulose" <suzuki.poulose@arm.com> - 2016-01-25 12:30 +0100

#1316507 — [PATCH v6 00/12] arm-cci: PMU driver updates

This series includes:

 - Simplified sysfs attribute handling for CCI PMU (Patch 1)
 - Work around for writing to CCI-500/550(introduced later) PMU
   counters (Patches 2-10)
 - Support for CCI-550 PMU (11-12) with Acked-bys.

Since all of these are related I am clubbing it all in one series
so that it is easier to carry them around (and merge it possibly).

The CCI PMU driver sets the event counter to the half of the maximum
value(2^31) it can count before we start the counters via
pmu_event_set_period(). This is done to give us the best chance to
handle the overflow interrupt, taking care of extreme interrupt latencies.

However, CCI-500 comes with advanced power saving schemes, which disables
the clock to the event counters unless the counters are enabled to count
(PMCR.CEN). This prevents the driver from writing the period to the
counters before starting them.  Also, there is no way we can reset the
individual event counter to 0 (PMCR.RST resets all the counters, losing
their current readings). However the value of the counter is preserved and
could be read back, when the counters are not enabled.

So we cannot reliably use the counters and compute the number of events
generated during the sampling period since we don't have the value of the
counter at start.

Here are the possible solutions:

 1) Disable clock gating on CCI-500 by setting Control_Override_Reg[bit3].
    - The Control_Override_Reg is secure (and hence not programmable from
      Linux), and also has an impact on power consumption.

 2) Change the order of operations
	i.e,
	a) Program and enable individual counters
	b) Enable counting on all the counters by setting PMCR.CEN
	c) Write the period to the individual counters
	d) Disable the counters
    - This could cause in unnecessary noise in the other counters and is
      costly (we should repeat this for all enabled counters).

 3) Don't set the counter value, instead use the current count as the
    starting count and compute the delta at the end of sampling.

 4) Modified version of 2, which disables all the other counters, except
    the target counter, with the target counter programmed with an invalid
    event code(which guarantees that the counter won't change during the
    operation).

This patch implements option 4 for CCI-500(and CCI-550). CCI-400 behavior
remains unchanged.

The tree on top of 4.5-rc1 is available at :

    git://linux-arm.org/linux-skp.git   cci-updates/4.5-rc1

Changes since V5:
 - Delay writes from irq handler by disabling the PMU (suggested by Mark Rutland)
   unifying the counter programming to __pmu_enable

Changes since V4:
 - Drop transaction hooks. Instead, group and delay the writes to pmu_enable().
 - Rebased to 4.4-rc8

Changes sinces V3:
 - Added transaction hooks to batch the writes to PMU counters for
   group events.
 - Pulled ARM CCI 550 PMU support patches

Changes since V2:
 - Rebased to 4.4-rc1 + Mark's patch to simply PMU syfs attributes [1]
 - Address comments on v2.
 - Split the introduction of write_counter hook to a separate patch

Changes since V1:
 - Choose 4 instead of 3 above, suggested by Mark Rutland

Mark Rutland (1):
  arm-cci: simplify sysfs attr handling

Suzuki K. Poulose (11):
  arm-cci: Group writes to counter
  arm-cci: Refactor CCI PMU enable/disable methods
  arm-cci: Delay PMU counter writes to pmu::pmu_enable
  arm-cci: write_counter: Remove redundant check
  arm-cci: Get the status of a counter
  arm-cci: Add routines to save/restore all counters
  __cci_pmu_enable: Make counter sync optional
  arm-cci: Provide hook for writing to PMU counters
  arm-cci: CCI-500: Work around PMU counter writes
  arm-cci500: Rearrange PMU driver for code sharing with CCI-550 PMU
  arm-cci: CoreLink CCI-550 PMU driver

 Documentation/devicetree/bindings/arm/cci.txt |    2 +
 drivers/bus/Kconfig                           |   10 +-
 drivers/bus/arm-cci.c                         |  611 +++++++++++++++++--------
 3 files changed, 427 insertions(+), 196 deletions(-)

-- 
1.7.9.5

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#1316509 — [PATCH v6 03/12] arm-cci: Refactor CCI PMU enable/disable methods

This patch refactors the CCI PMU driver code a little bit to
make it easier share the code for enabling/disabling the CCI
PMU. This will be used by the hooks to work around the special cases
where writing to a counter is not always that easy(e.g, CCI-500)

No functional changes.

Cc: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
---
 drivers/bus/arm-cci.c |   32 ++++++++++++++++++++++----------
 1 file changed, 22 insertions(+), 10 deletions(-)

diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
index 936fa9b..1e1e9a3 100644
--- a/drivers/bus/arm-cci.c
+++ b/drivers/bus/arm-cci.c
@@ -606,6 +606,26 @@ static int cci500_validate_hw_event(struct cci_pmu *cci_pmu,
 }
 #endif	/* CONFIG_ARM_CCI500_PMU */
 
+/* Should be called with cci_pmu->hw_events->pmu_lock held */
+static void __cci_pmu_enable(void)
+{
+	u32 val;
+
+	/* Enable all the PMU counters. */
+	val = readl_relaxed(cci_ctrl_base + CCI_PMCR) | CCI_PMCR_CEN;
+	writel(val, cci_ctrl_base + CCI_PMCR);
+}
+
+/* Should be called with cci_pmu->hw_events->pmu_lock held */
+static void __cci_pmu_disable(void)
+{
+	u32 val;
+
+	/* Disable all the PMU counters. */
+	val = readl_relaxed(cci_ctrl_base + CCI_PMCR) & ~CCI_PMCR_CEN;
+	writel(val, cci_ctrl_base + CCI_PMCR);
+}
+
 static ssize_t cci_pmu_format_show(struct device *dev,
 			struct device_attribute *attr, char *buf)
 {
@@ -895,16 +915,12 @@ static void cci_pmu_enable(struct pmu *pmu)
 	struct cci_pmu_hw_events *hw_events = &cci_pmu->hw_events;
 	int enabled = bitmap_weight(hw_events->used_mask, cci_pmu->num_cntrs);
 	unsigned long flags;
-	u32 val;
 
 	if (!enabled)
 		return;
 
 	raw_spin_lock_irqsave(&hw_events->pmu_lock, flags);
-
-	/* Enable all the PMU counters. */
-	val = readl_relaxed(cci_ctrl_base + CCI_PMCR) | CCI_PMCR_CEN;
-	writel(val, cci_ctrl_base + CCI_PMCR);
+	__cci_pmu_enable();
 	raw_spin_unlock_irqrestore(&hw_events->pmu_lock, flags);
 
 }
@@ -914,13 +930,9 @@ static void cci_pmu_disable(struct pmu *pmu)
 	struct cci_pmu *cci_pmu = to_cci_pmu(pmu);
 	struct cci_pmu_hw_events *hw_events = &cci_pmu->hw_events;
 	unsigned long flags;
-	u32 val;
 
 	raw_spin_lock_irqsave(&hw_events->pmu_lock, flags);
-
-	/* Disable all the PMU counters. */
-	val = readl_relaxed(cci_ctrl_base + CCI_PMCR) & ~CCI_PMCR_CEN;
-	writel(val, cci_ctrl_base + CCI_PMCR);
+	__cci_pmu_disable();
 	raw_spin_unlock_irqrestore(&hw_events->pmu_lock, flags);
 }
 
-- 
1.7.9.5

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#1316510 — [PATCH v6 11/12] arm-cci500: Rearrange PMU driver for code sharing with CCI-550 PMU

CCI-550 PMU shares most of the CCI-500 PMU attributes including the
event format, PMU event codes. The only difference is an additional
master interface (MI6 - 0xe). Hence we share the driver code for both,
except for a model specific event validate method.
This patch renames the common CCI500 symbols to CCI5xx, including the
Kconfig symbol.

No functional changes to the PMU driver.

Acked-by: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
---
 drivers/bus/Kconfig   |    2 +-
 drivers/bus/arm-cci.c |  218 +++++++++++++++++++++++++------------------------
 2 files changed, 112 insertions(+), 108 deletions(-)

diff --git a/drivers/bus/Kconfig b/drivers/bus/Kconfig
index 129d47b..e25a850 100644
--- a/drivers/bus/Kconfig
+++ b/drivers/bus/Kconfig
@@ -34,7 +34,7 @@ config ARM_CCI400_PORT_CTRL
 	  Low level power management driver for CCI400 cache coherent
 	  interconnect for ARM platforms.
 
-config ARM_CCI500_PMU
+config ARM_CCI5xx_PMU
 	bool "ARM CCI500 PMU support"
 	depends on (ARM && CPU_V7) || ARM64
 	depends on PERF_EVENTS
diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
index 69a8a61..3246769 100644
--- a/drivers/bus/arm-cci.c
+++ b/drivers/bus/arm-cci.c
@@ -52,7 +52,7 @@ static const struct of_device_id arm_cci_matches[] = {
 #ifdef CONFIG_ARM_CCI400_COMMON
 	{.compatible = "arm,cci-400", .data = CCI400_PORTS_DATA },
 #endif
-#ifdef CONFIG_ARM_CCI500_PMU
+#ifdef CONFIG_ARM_CCI5xx_PMU
 	{ .compatible = "arm,cci-500", },
 #endif
 	{},
@@ -95,7 +95,7 @@ static const struct of_device_id arm_cci_matches[] = {
 enum {
 	CCI_IF_SLAVE,
 	CCI_IF_MASTER,
-#ifdef CONFIG_ARM_CCI500_PMU
+#ifdef CONFIG_ARM_CCI5xx_PMU
 	CCI_IF_GLOBAL,
 #endif
 	CCI_IF_MAX,
@@ -157,7 +157,7 @@ enum cci_models {
 	CCI400_R0,
 	CCI400_R1,
 #endif
-#ifdef CONFIG_ARM_CCI500_PMU
+#ifdef CONFIG_ARM_CCI5xx_PMU
 	CCI500_R0,
 #endif
 	CCI_MODEL_MAX
@@ -429,73 +429,67 @@ static inline struct cci_pmu_model *probe_cci_model(struct platform_device *pdev
 }
 #endif	/* CONFIG_ARM_CCI400_PMU */
 
-#ifdef CONFIG_ARM_CCI500_PMU
+#ifdef CONFIG_ARM_CCI5xx_PMU
 
 /*
- * CCI500 provides 8 independent event counters that can count
- * any of the events available.
- *
- * CCI500 PMU event id is an 9-bit value made of two parts.
+ * CCI5xx PMU event id is an 9-bit value made of two parts.
  *	 bits [8:5] - Source for the event
- *		      0x0-0x6 - Slave interfaces
- *		      0x8-0xD - Master interfaces
- *		      0xf     - Global Events
- *		      0x7,0xe - Reserved
- *
  *	 bits [4:0] - Event code (specific to type of interface)
+ *
+ *
  */
 
 /* Port ids */
-#define CCI500_PORT_S0			0x0
-#define CCI500_PORT_S1			0x1
-#define CCI500_PORT_S2			0x2
-#define CCI500_PORT_S3			0x3
-#define CCI500_PORT_S4			0x4
-#define CCI500_PORT_S5			0x5
-#define CCI500_PORT_S6			0x6
-
-#define CCI500_PORT_M0			0x8
-#define CCI500_PORT_M1			0x9
-#define CCI500_PORT_M2			0xa
-#define CCI500_PORT_M3			0xb
-#define CCI500_PORT_M4			0xc
-#define CCI500_PORT_M5			0xd
-
-#define CCI500_PORT_GLOBAL 		0xf
-
-#define CCI500_PMU_EVENT_MASK		0x1ffUL
-#define CCI500_PMU_EVENT_SOURCE_SHIFT	0x5
-#define CCI500_PMU_EVENT_SOURCE_MASK	0xf
-#define CCI500_PMU_EVENT_CODE_SHIFT	0x0
-#define CCI500_PMU_EVENT_CODE_MASK	0x1f
-
-#define CCI500_PMU_EVENT_SOURCE(event)	\
-	((event >> CCI500_PMU_EVENT_SOURCE_SHIFT) & CCI500_PMU_EVENT_SOURCE_MASK)
-#define CCI500_PMU_EVENT_CODE(event)	\
-	((event >> CCI500_PMU_EVENT_CODE_SHIFT) & CCI500_PMU_EVENT_CODE_MASK)
-
-#define CCI500_SLAVE_PORT_MIN_EV	0x00
-#define CCI500_SLAVE_PORT_MAX_EV	0x1f
-#define CCI500_MASTER_PORT_MIN_EV	0x00
-#define CCI500_MASTER_PORT_MAX_EV	0x06
-#define CCI500_GLOBAL_PORT_MIN_EV	0x00
-#define CCI500_GLOBAL_PORT_MAX_EV	0x0f
-
-
-#define CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(_name, _config) \
-	CCI_EXT_ATTR_ENTRY(_name, cci500_pmu_global_event_show, \
+#define CCI5xx_PORT_S0			0x0
+#define CCI5xx_PORT_S1			0x1
+#define CCI5xx_PORT_S2			0x2
+#define CCI5xx_PORT_S3			0x3
+#define CCI5xx_PORT_S4			0x4
+#define CCI5xx_PORT_S5			0x5
+#define CCI5xx_PORT_S6			0x6
+
+#define CCI5xx_PORT_M0			0x8
+#define CCI5xx_PORT_M1			0x9
+#define CCI5xx_PORT_M2			0xa
+#define CCI5xx_PORT_M3			0xb
+#define CCI5xx_PORT_M4			0xc
+#define CCI5xx_PORT_M5			0xd
+
+#define CCI5xx_PORT_GLOBAL		0xf
+
+#define CCI5xx_PMU_EVENT_MASK		0x1ffUL
+#define CCI5xx_PMU_EVENT_SOURCE_SHIFT	0x5
+#define CCI5xx_PMU_EVENT_SOURCE_MASK	0xf
+#define CCI5xx_PMU_EVENT_CODE_SHIFT	0x0
+#define CCI5xx_PMU_EVENT_CODE_MASK	0x1f
+
+#define CCI5xx_PMU_EVENT_SOURCE(event)	\
+	((event >> CCI5xx_PMU_EVENT_SOURCE_SHIFT) & CCI5xx_PMU_EVENT_SOURCE_MASK)
+#define CCI5xx_PMU_EVENT_CODE(event)	\
+	((event >> CCI5xx_PMU_EVENT_CODE_SHIFT) & CCI5xx_PMU_EVENT_CODE_MASK)
+
+#define CCI5xx_SLAVE_PORT_MIN_EV	0x00
+#define CCI5xx_SLAVE_PORT_MAX_EV	0x1f
+#define CCI5xx_MASTER_PORT_MIN_EV	0x00
+#define CCI5xx_MASTER_PORT_MAX_EV	0x06
+#define CCI5xx_GLOBAL_PORT_MIN_EV	0x00
+#define CCI5xx_GLOBAL_PORT_MAX_EV	0x0f
+
+
+#define CCI5xx_GLOBAL_EVENT_EXT_ATTR_ENTRY(_name, _config) \
+	CCI_EXT_ATTR_ENTRY(_name, cci5xx_pmu_global_event_show, \
 					(unsigned long) _config)
 
-static ssize_t cci500_pmu_global_event_show(struct device *dev,
+static ssize_t cci5xx_pmu_global_event_show(struct device *dev,
 				struct device_attribute *attr, char *buf);
 
-static struct attribute *cci500_pmu_format_attrs[] = {
+static struct attribute *cci5xx_pmu_format_attrs[] = {
 	CCI_FORMAT_EXT_ATTR_ENTRY(event, "config:0-4"),
 	CCI_FORMAT_EXT_ATTR_ENTRY(source, "config:5-8"),
 	NULL,
 };
 
-static struct attribute *cci500_pmu_event_attrs[] = {
+static struct attribute *cci5xx_pmu_event_attrs[] = {
 	/* Slave events */
 	CCI_EVENT_EXT_ATTR_ENTRY(si_rrq_hs_arvalid, 0x0),
 	CCI_EVENT_EXT_ATTR_ENTRY(si_rrq_dev, 0x1),
@@ -540,64 +534,73 @@ static struct attribute *cci500_pmu_event_attrs[] = {
 	CCI_EVENT_EXT_ATTR_ENTRY(mi_w_resp_stall, 0x6),
 
 	/* Global events */
-	CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_access_filter_bank_0_1, 0x0),
-	CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_access_filter_bank_2_3, 0x1),
-	CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_access_filter_bank_4_5, 0x2),
-	CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_access_filter_bank_6_7, 0x3),
-	CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_access_miss_filter_bank_0_1, 0x4),
-	CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_access_miss_filter_bank_2_3, 0x5),
-	CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_access_miss_filter_bank_4_5, 0x6),
-	CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_access_miss_filter_bank_6_7, 0x7),
-	CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_back_invalidation, 0x8),
-	CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_stall_alloc_busy, 0x9),
-	CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_stall_tt_full, 0xA),
-	CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_wrq, 0xB),
-	CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_cd_hs, 0xC),
-	CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_rq_stall_addr_hazard, 0xD),
-	CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snopp_rq_stall_tt_full, 0xE),
-	CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_rq_tzmp1_prot, 0xF),
+	CCI5xx_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_access_filter_bank_0_1, 0x0),
+	CCI5xx_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_access_filter_bank_2_3, 0x1),
+	CCI5xx_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_access_filter_bank_4_5, 0x2),
+	CCI5xx_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_access_filter_bank_6_7, 0x3),
+	CCI5xx_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_access_miss_filter_bank_0_1, 0x4),
+	CCI5xx_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_access_miss_filter_bank_2_3, 0x5),
+	CCI5xx_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_access_miss_filter_bank_4_5, 0x6),
+	CCI5xx_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_access_miss_filter_bank_6_7, 0x7),
+	CCI5xx_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_back_invalidation, 0x8),
+	CCI5xx_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_stall_alloc_busy, 0x9),
+	CCI5xx_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_stall_tt_full, 0xA),
+	CCI5xx_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_wrq, 0xB),
+	CCI5xx_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_cd_hs, 0xC),
+	CCI5xx_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_rq_stall_addr_hazard, 0xD),
+	CCI5xx_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snopp_rq_stall_tt_full, 0xE),
+	CCI5xx_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_rq_tzmp1_prot, 0xF),
 	NULL
 };
 
-static ssize_t cci500_pmu_global_event_show(struct device *dev,
+static ssize_t cci5xx_pmu_global_event_show(struct device *dev,
 				struct device_attribute *attr, char *buf)
 {
 	struct dev_ext_attribute *eattr = container_of(attr,
 					struct dev_ext_attribute, attr);
 	/* Global events have single fixed source code */
 	return snprintf(buf, PAGE_SIZE, "event=0x%lx,source=0x%x\n",
-				(unsigned long)eattr->var, CCI500_PORT_GLOBAL);
+				(unsigned long)eattr->var, CCI5xx_PORT_GLOBAL);
 }
 
+/*
+ * CCI500 provides 8 independent event counters that can count
+ * any of the events available.
+ * CCI500 PMU event source ids
+ *	0x0-0x6 - Slave interfaces
+ *	0x8-0xD - Master interfaces
+ *	0xf     - Global Events
+ *	0x7,0xe - Reserved
+ */
 static int cci500_validate_hw_event(struct cci_pmu *cci_pmu,
 					unsigned long hw_event)
 {
-	u32 ev_source = CCI500_PMU_EVENT_SOURCE(hw_event);
-	u32 ev_code = CCI500_PMU_EVENT_CODE(hw_event);
+	u32 ev_source = CCI5xx_PMU_EVENT_SOURCE(hw_event);
+	u32 ev_code = CCI5xx_PMU_EVENT_CODE(hw_event);
 	int if_type;
 
-	if (hw_event & ~CCI500_PMU_EVENT_MASK)
+	if (hw_event & ~CCI5xx_PMU_EVENT_MASK)
 		return -ENOENT;
 
 	switch (ev_source) {
-	case CCI500_PORT_S0:
-	case CCI500_PORT_S1:
-	case CCI500_PORT_S2:
-	case CCI500_PORT_S3:
-	case CCI500_PORT_S4:
-	case CCI500_PORT_S5:
-	case CCI500_PORT_S6:
+	case CCI5xx_PORT_S0:
+	case CCI5xx_PORT_S1:
+	case CCI5xx_PORT_S2:
+	case CCI5xx_PORT_S3:
+	case CCI5xx_PORT_S4:
+	case CCI5xx_PORT_S5:
+	case CCI5xx_PORT_S6:
 		if_type = CCI_IF_SLAVE;
 		break;
-	case CCI500_PORT_M0:
-	case CCI500_PORT_M1:
-	case CCI500_PORT_M2:
-	case CCI500_PORT_M3:
-	case CCI500_PORT_M4:
-	case CCI500_PORT_M5:
+	case CCI5xx_PORT_M0:
+	case CCI5xx_PORT_M1:
+	case CCI5xx_PORT_M2:
+	case CCI5xx_PORT_M3:
+	case CCI5xx_PORT_M4:
+	case CCI5xx_PORT_M5:
 		if_type = CCI_IF_MASTER;
 		break;
-	case CCI500_PORT_GLOBAL:
+	case CCI5xx_PORT_GLOBAL:
 		if_type = CCI_IF_GLOBAL;
 		break;
 	default:
@@ -610,7 +613,8 @@ static int cci500_validate_hw_event(struct cci_pmu *cci_pmu,
 
 	return -ENOENT;
 }
-#endif	/* CONFIG_ARM_CCI500_PMU */
+
+#endif	/* CONFIG_ARM_CCI5xx_PMU */
 
 /*
  * Program the CCI PMU counters which have PERF_HES_ARCH set
@@ -890,7 +894,7 @@ static void pmu_write_counters(struct cci_pmu *cci_pmu, unsigned long *mask)
 		__pmu_write_counters(cci_pmu, mask);
 }
 
-#ifdef CONFIG_ARM_CCI500_PMU
+#ifdef CONFIG_ARM_CCI5xx_PMU
 
 /*
  * CCI-500 has advanced power saving policies, which could gate the
@@ -920,9 +924,9 @@ static void pmu_write_counters(struct cci_pmu *cci_pmu, unsigned long *mask)
  * assigned a valid code for step(2). We use the highest possible
  * event code (0x1f) for the master interface 0.
  */
-#define CCI500_INVALID_EVENT	((CCI500_PORT_M0 << CCI500_PMU_EVENT_SOURCE_SHIFT) | \
-				 (CCI500_PMU_EVENT_CODE_MASK << CCI500_PMU_EVENT_CODE_SHIFT))
-static void cci500_pmu_write_counters(struct cci_pmu *cci_pmu, unsigned long *mask)
+#define CCI5xx_INVALID_EVENT	((CCI5xx_PORT_M0 << CCI5xx_PMU_EVENT_SOURCE_SHIFT) | \
+				 (CCI5xx_PMU_EVENT_CODE_MASK << CCI5xx_PMU_EVENT_CODE_SHIFT))
+static void cci5xx_pmu_write_counters(struct cci_pmu *cci_pmu, unsigned long *mask)
 {
 	int i;
 	DECLARE_BITMAP(saved_mask, cci_pmu->num_cntrs);
@@ -942,7 +946,7 @@ static void cci500_pmu_write_counters(struct cci_pmu *cci_pmu, unsigned long *ma
 		if (WARN_ON(!event))
 			continue;
 
-		pmu_set_event(cci_pmu, i, CCI500_INVALID_EVENT);
+		pmu_set_event(cci_pmu, i, CCI5xx_INVALID_EVENT);
 		pmu_enable_counter(cci_pmu, i);
 		pmu_write_counter(cci_pmu,
 				  (u32)local64_read(&event->hw.prev_count), i);
@@ -955,7 +959,7 @@ static void cci500_pmu_write_counters(struct cci_pmu *cci_pmu, unsigned long *ma
 	pmu_restore_counters(cci_pmu, saved_mask);
 }
 
-#endif	/* CONFIG_ARM_CCI500_PMU */
+#endif	/* CONFIG_ARM_CCI5xx_PMU */
 
 static u64 pmu_event_update(struct perf_event *event)
 {
@@ -1518,30 +1522,30 @@ static struct cci_pmu_model cci_pmu_models[] = {
 		.get_event_idx = cci400_get_event_idx,
 	},
 #endif
-#ifdef CONFIG_ARM_CCI500_PMU
+#ifdef CONFIG_ARM_CCI5xx_PMU
 	[CCI500_R0] = {
 		.name = "CCI_500",
 		.fixed_hw_cntrs = 0,
 		.num_hw_cntrs = 8,
 		.cntr_size = SZ_64K,
-		.format_attrs = cci500_pmu_format_attrs,
-		.event_attrs = cci500_pmu_event_attrs,
+		.format_attrs = cci5xx_pmu_format_attrs,
+		.event_attrs = cci5xx_pmu_event_attrs,
 		.event_ranges = {
 			[CCI_IF_SLAVE] = {
-				CCI500_SLAVE_PORT_MIN_EV,
-				CCI500_SLAVE_PORT_MAX_EV,
+				CCI5xx_SLAVE_PORT_MIN_EV,
+				CCI5xx_SLAVE_PORT_MAX_EV,
 			},
 			[CCI_IF_MASTER] = {
-				CCI500_MASTER_PORT_MIN_EV,
-				CCI500_MASTER_PORT_MAX_EV,
+				CCI5xx_MASTER_PORT_MIN_EV,
+				CCI5xx_MASTER_PORT_MAX_EV,
 			},
 			[CCI_IF_GLOBAL] = {
-				CCI500_GLOBAL_PORT_MIN_EV,
-				CCI500_GLOBAL_PORT_MAX_EV,
+				CCI5xx_GLOBAL_PORT_MIN_EV,
+				CCI5xx_GLOBAL_PORT_MAX_EV,
 			},
 		},
 		.validate_hw_event = cci500_validate_hw_event,
-		.write_counters	= cci500_pmu_write_counters,
+		.write_counters	= cci5xx_pmu_write_counters,
 	},
 #endif
 };
@@ -1561,7 +1565,7 @@ static const struct of_device_id arm_cci_pmu_matches[] = {
 		.data	= &cci_pmu_models[CCI400_R1],
 	},
 #endif
-#ifdef CONFIG_ARM_CCI500_PMU
+#ifdef CONFIG_ARM_CCI5xx_PMU
 	{
 		.compatible = "arm,cci-500-pmu,r0",
 		.data = &cci_pmu_models[CCI500_R0],
-- 
1.7.9.5

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#1316516 — [PATCH v6 05/12] arm-cci: write_counter: Remove redundant check

pmu_write_counter() is now only called from pmu_write_counters(),
which does so for each set index in the given mask, bounded by
cci_pmu->num_cntrs. So, there is no need for an extra check to
make sure the given counter is valid inside pmu_write_counter.
This patch gets rid of that.

Cc: Punit Agrawal <punit.agrawal@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
---
 drivers/bus/arm-cci.c |   13 +++----------
 1 file changed, 3 insertions(+), 10 deletions(-)

diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
index df04b625..4710d51 100644
--- a/drivers/bus/arm-cci.c
+++ b/drivers/bus/arm-cci.c
@@ -814,16 +814,9 @@ static u32 pmu_read_counter(struct perf_event *event)
 	return value;
 }
 
-static void pmu_write_counter(struct perf_event *event, u32 value)
+static void pmu_write_counter(struct cci_pmu *cci_pmu, u32 value, int idx)
 {
-	struct cci_pmu *cci_pmu = to_cci_pmu(event->pmu);
-	struct hw_perf_event *hw_counter = &event->hw;
-	int idx = hw_counter->idx;
-
-	if (unlikely(!pmu_is_valid_counter(cci_pmu, idx)))
-		dev_err(&cci_pmu->plat_device->dev, "Invalid CCI PMU counter %d\n", idx);
-	else
-		pmu_write_register(cci_pmu, value, idx, CCI_PMU_CNTR);
+	pmu_write_register(cci_pmu, value, idx, CCI_PMU_CNTR);
 }
 
 static void pmu_write_counters(struct cci_pmu *cci_pmu, unsigned long *mask)
@@ -836,7 +829,7 @@ static void pmu_write_counters(struct cci_pmu *cci_pmu, unsigned long *mask)
 
 		if (WARN_ON(!event))
 			continue;
-		pmu_write_counter(event, (u32)local64_read(&event->hw.prev_count));
+		pmu_write_counter(cci_pmu, (u32)local64_read(&event->hw.prev_count), i);
 	}
 }
 
-- 
1.7.9.5

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#1316518 — [PATCH v6 01/12] arm-cci: simplify sysfs attr handling

From: Mark Rutland <mark.rutland@arm.com>

There's no need to dynamically initialise attribute pointers when we can
get the compiler to do it for us. We also don't need a dev_ext_attribute
for the cpumask, as the drvdata for a PMU device is a pointer to struct
pmu.

Signed-off-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
Reviewed-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
Cc: Punit Agrawal <punit.agrawal@arm.com>
---
 drivers/bus/arm-cci.c |  100 +++++++++++++------------------------------------
 1 file changed, 25 insertions(+), 75 deletions(-)

diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
index 577cc4b..ee47e6b 100644
--- a/drivers/bus/arm-cci.c
+++ b/drivers/bus/arm-cci.c
@@ -121,10 +121,8 @@ struct cci_pmu_model {
 	u32 fixed_hw_cntrs;
 	u32 num_hw_cntrs;
 	u32 cntr_size;
-	u64 nformat_attrs;
-	u64 nevent_attrs;
-	struct dev_ext_attribute *format_attrs;
-	struct dev_ext_attribute *event_attrs;
+	struct attribute **format_attrs;
+	struct attribute **event_attrs;
 	struct event_range event_ranges[CCI_IF_MAX];
 	int (*validate_hw_event)(struct cci_pmu *, unsigned long);
 	int (*get_event_idx)(struct cci_pmu *, struct cci_pmu_hw_events *, unsigned long);
@@ -166,8 +164,10 @@ static ssize_t cci_pmu_format_show(struct device *dev,
 static ssize_t cci_pmu_event_show(struct device *dev,
 			struct device_attribute *attr, char *buf);
 
-#define CCI_EXT_ATTR_ENTRY(_name, _func, _config) \
-	{ __ATTR(_name, S_IRUGO, _func, NULL), (void *)_config }
+#define CCI_EXT_ATTR_ENTRY(_name, _func, _config) 				\
+	&((struct dev_ext_attribute[]) {					\
+		{ __ATTR(_name, S_IRUGO, _func, NULL), (void *)_config }	\
+	})[0].attr.attr
 
 #define CCI_FORMAT_EXT_ATTR_ENTRY(_name, _config) \
 	CCI_EXT_ATTR_ENTRY(_name, cci_pmu_format_show, (char *)_config)
@@ -242,12 +242,13 @@ enum cci400_perf_events {
 static ssize_t cci400_pmu_cycle_event_show(struct device *dev,
 			struct device_attribute *attr, char *buf);
 
-static struct dev_ext_attribute cci400_pmu_format_attrs[] = {
+static struct attribute *cci400_pmu_format_attrs[] = {
 	CCI_FORMAT_EXT_ATTR_ENTRY(event, "config:0-4"),
 	CCI_FORMAT_EXT_ATTR_ENTRY(source, "config:5-7"),
+	NULL
 };
 
-static struct dev_ext_attribute cci400_r0_pmu_event_attrs[] = {
+static struct attribute *cci400_r0_pmu_event_attrs[] = {
 	/* Slave events */
 	CCI_EVENT_EXT_ATTR_ENTRY(si_rrq_hs_any, 0x0),
 	CCI_EVENT_EXT_ATTR_ENTRY(si_rrq_hs_device, 0x01),
@@ -279,9 +280,10 @@ static struct dev_ext_attribute cci400_r0_pmu_event_attrs[] = {
 	CCI_EVENT_EXT_ATTR_ENTRY(mi_wrq_stall_tt_full, 0x1A),
 	/* Special event for cycles counter */
 	CCI400_CYCLE_EVENT_EXT_ATTR_ENTRY(cycles, 0xff),
+	NULL
 };
 
-static struct dev_ext_attribute cci400_r1_pmu_event_attrs[] = {
+static struct attribute *cci400_r1_pmu_event_attrs[] = {
 	/* Slave events */
 	CCI_EVENT_EXT_ATTR_ENTRY(si_rrq_hs_any, 0x0),
 	CCI_EVENT_EXT_ATTR_ENTRY(si_rrq_hs_device, 0x01),
@@ -325,6 +327,7 @@ static struct dev_ext_attribute cci400_r1_pmu_event_attrs[] = {
 	CCI_EVENT_EXT_ATTR_ENTRY(mi_wrq_unique_or_line_unique_addr_hazard, 0x11),
 	/* Special event for cycles counter */
 	CCI400_CYCLE_EVENT_EXT_ATTR_ENTRY(cycles, 0xff),
+	NULL
 };
 
 static ssize_t cci400_pmu_cycle_event_show(struct device *dev,
@@ -480,12 +483,13 @@ static inline struct cci_pmu_model *probe_cci_model(struct platform_device *pdev
 static ssize_t cci500_pmu_global_event_show(struct device *dev,
 				struct device_attribute *attr, char *buf);
 
-static struct dev_ext_attribute cci500_pmu_format_attrs[] = {
+static struct attribute *cci500_pmu_format_attrs[] = {
 	CCI_FORMAT_EXT_ATTR_ENTRY(event, "config:0-4"),
 	CCI_FORMAT_EXT_ATTR_ENTRY(source, "config:5-8"),
+	NULL,
 };
 
-static struct dev_ext_attribute cci500_pmu_event_attrs[] = {
+static struct attribute *cci500_pmu_event_attrs[] = {
 	/* Slave events */
 	CCI_EVENT_EXT_ATTR_ENTRY(si_rrq_hs_arvalid, 0x0),
 	CCI_EVENT_EXT_ATTR_ENTRY(si_rrq_dev, 0x1),
@@ -546,6 +550,7 @@ static struct dev_ext_attribute cci500_pmu_event_attrs[] = {
 	CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_rq_stall_addr_hazard, 0xD),
 	CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snopp_rq_stall_tt_full, 0xE),
 	CCI500_GLOBAL_EVENT_EXT_ATTR_ENTRY(cci_snoop_rq_tzmp1_prot, 0xF),
+	NULL
 };
 
 static ssize_t cci500_pmu_global_event_show(struct device *dev,
@@ -1176,9 +1181,8 @@ static int cci_pmu_event_init(struct perf_event *event)
 static ssize_t pmu_cpumask_attr_show(struct device *dev,
 				     struct device_attribute *attr, char *buf)
 {
-	struct dev_ext_attribute *eattr = container_of(attr,
-					struct dev_ext_attribute, attr);
-	struct cci_pmu *cci_pmu = eattr->var;
+	struct pmu *pmu = dev_get_drvdata(dev);
+	struct cci_pmu *cci_pmu = to_cci_pmu(pmu);
 
 	int n = scnprintf(buf, PAGE_SIZE - 1, "%*pbl",
 			  cpumask_pr_args(&cci_pmu->cpus));
@@ -1187,13 +1191,11 @@ static ssize_t pmu_cpumask_attr_show(struct device *dev,
 	return n;
 }
 
-static struct dev_ext_attribute pmu_cpumask_attr = {
-	__ATTR(cpumask, S_IRUGO, pmu_cpumask_attr_show, NULL),
-	NULL,		/* Populated in cci_pmu_init */
-};
+static struct device_attribute pmu_cpumask_attr =
+	__ATTR(cpumask, S_IRUGO, pmu_cpumask_attr_show, NULL);
 
 static struct attribute *pmu_attrs[] = {
-	&pmu_cpumask_attr.attr.attr,
+	&pmu_cpumask_attr.attr,
 	NULL,
 };
 
@@ -1218,60 +1220,14 @@ static const struct attribute_group *pmu_attr_groups[] = {
 	NULL
 };
 
-static struct attribute **alloc_attrs(struct platform_device *pdev,
-				int n, struct dev_ext_attribute *source)
-{
-	int i;
-	struct attribute **attrs;
-
-	/* Alloc n + 1 (for terminating NULL) */
-	attrs  = devm_kcalloc(&pdev->dev, n + 1, sizeof(struct attribute *),
-								GFP_KERNEL);
-	if (!attrs)
-		return attrs;
-	for(i = 0; i < n; i++)
-		attrs[i] = &source[i].attr.attr;
-	return attrs;
-}
-
-static int cci_pmu_init_attrs(struct cci_pmu *cci_pmu, struct platform_device *pdev)
-{
-	const struct cci_pmu_model *model = cci_pmu->model;
-	struct attribute **attrs;
-
-	/*
-	 * All allocations below are managed, hence doesn't need to be
-	 * free'd explicitly in case of an error.
-	 */
-
-	if (model->nevent_attrs) {
-		attrs = alloc_attrs(pdev, model->nevent_attrs,
-						model->event_attrs);
-		if (!attrs)
-			return -ENOMEM;
-		pmu_event_attr_group.attrs = attrs;
-	}
-	if (model->nformat_attrs) {
-		attrs = alloc_attrs(pdev, model->nformat_attrs,
-						 model->format_attrs);
-		if (!attrs)
-			return -ENOMEM;
-		pmu_format_attr_group.attrs = attrs;
-	}
-	pmu_cpumask_attr.var = cci_pmu;
-
-	return 0;
-}
-
 static int cci_pmu_init(struct cci_pmu *cci_pmu, struct platform_device *pdev)
 {
-	char *name = cci_pmu->model->name;
+	const struct cci_pmu_model *model = cci_pmu->model;
+	char *name = model->name;
 	u32 num_cntrs;
-	int rc;
 
-	rc = cci_pmu_init_attrs(cci_pmu, pdev);
-	if (rc)
-		return rc;
+	pmu_event_attr_group.attrs = model->event_attrs;
+	pmu_format_attr_group.attrs = model->format_attrs;
 
 	cci_pmu->pmu = (struct pmu) {
 		.name		= cci_pmu->model->name,
@@ -1336,9 +1292,7 @@ static struct cci_pmu_model cci_pmu_models[] = {
 		.num_hw_cntrs = 4,
 		.cntr_size = SZ_4K,
 		.format_attrs = cci400_pmu_format_attrs,
-		.nformat_attrs = ARRAY_SIZE(cci400_pmu_format_attrs),
 		.event_attrs = cci400_r0_pmu_event_attrs,
-		.nevent_attrs = ARRAY_SIZE(cci400_r0_pmu_event_attrs),
 		.event_ranges = {
 			[CCI_IF_SLAVE] = {
 				CCI400_R0_SLAVE_PORT_MIN_EV,
@@ -1358,9 +1312,7 @@ static struct cci_pmu_model cci_pmu_models[] = {
 		.num_hw_cntrs = 4,
 		.cntr_size = SZ_4K,
 		.format_attrs = cci400_pmu_format_attrs,
-		.nformat_attrs = ARRAY_SIZE(cci400_pmu_format_attrs),
 		.event_attrs = cci400_r1_pmu_event_attrs,
-		.nevent_attrs = ARRAY_SIZE(cci400_r1_pmu_event_attrs),
 		.event_ranges = {
 			[CCI_IF_SLAVE] = {
 				CCI400_R1_SLAVE_PORT_MIN_EV,
@@ -1382,9 +1334,7 @@ static struct cci_pmu_model cci_pmu_models[] = {
 		.num_hw_cntrs = 8,
 		.cntr_size = SZ_64K,
 		.format_attrs = cci500_pmu_format_attrs,
-		.nformat_attrs = ARRAY_SIZE(cci500_pmu_format_attrs),
 		.event_attrs = cci500_pmu_event_attrs,
-		.nevent_attrs = ARRAY_SIZE(cci500_pmu_event_attrs),
 		.event_ranges = {
 			[CCI_IF_SLAVE] = {
 				CCI500_SLAVE_PORT_MIN_EV,
-- 
1.7.9.5

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#1316519 — [PATCH v6 06/12] arm-cci: Get the status of a counter

Add helper routines to check if the counter is enabled or not.

Cc: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
---
 drivers/bus/arm-cci.c |    6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
index 4710d51..f8f6a17 100644
--- a/drivers/bus/arm-cci.c
+++ b/drivers/bus/arm-cci.c
@@ -707,6 +707,12 @@ static void pmu_enable_counter(struct cci_pmu *cci_pmu, int idx)
 	pmu_write_register(cci_pmu, 1, idx, CCI_PMU_CNTR_CTRL);
 }
 
+static bool __maybe_unused
+pmu_counter_is_enabled(struct cci_pmu *cci_pmu, int idx)
+{
+	return (pmu_read_register(cci_pmu, idx, CCI_PMU_CNTR_CTRL) & 0x1) != 0;
+}
+
 static void pmu_set_event(struct cci_pmu *cci_pmu, int idx, unsigned long event)
 {
 	pmu_write_register(cci_pmu, event, idx, CCI_PMU_EVT_SEL);
-- 
1.7.9.5

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#1316520 — [PATCH v6 07/12] arm-cci: Add routines to save/restore all counters

Adds helper routines to disable the counter controls for
all the counters on the CCI PMU and restore it back, by
preserving the original state in caller provided mask.

Cc: Punit Agrawal <punit.agrawal@arm.com>
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
---
 drivers/bus/arm-cci.c |   38 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)

diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
index f8f6a17..997ad36 100644
--- a/drivers/bus/arm-cci.c
+++ b/drivers/bus/arm-cci.c
@@ -719,6 +719,44 @@ static void pmu_set_event(struct cci_pmu *cci_pmu, int idx, unsigned long event)
 }
 
 /*
+ * For all counters on the CCI-PMU, disable any 'enabled' counters,
+ * saving the changed counters in the mask, so that we can restore
+ * it later using pmu_restore_counters. The mask is private to the
+ * caller. We cannot rely on the used_mask maintained by the CCI_PMU
+ * as it only tells us if the counter is assigned to perf_event or not.
+ * The state of the perf_event cannot be locked by the PMU layer, hence
+ * we check the individual counter status (which can be locked by
+ * cci_pm->hw_events->pmu_lock).
+ *
+ * @mask should be initialised to empty by the caller.
+ */
+static void __maybe_unused
+pmu_save_counters(struct cci_pmu *cci_pmu, unsigned long *mask)
+{
+	int i;
+
+	for (i = 0; i < cci_pmu->num_cntrs; i++) {
+		if (pmu_counter_is_enabled(cci_pmu, i)) {
+			set_bit(i, mask);
+			pmu_disable_counter(cci_pmu, i);
+		}
+	}
+}
+
+/*
+ * Restore the status of the counters. Reversal of the pmu_save_counters().
+ * For each counter set in the mask, enable the counter back.
+ */
+static void __maybe_unused
+pmu_restore_counters(struct cci_pmu *cci_pmu, unsigned long *mask)
+{
+	int i;
+
+	for_each_set_bit(i, mask, cci_pmu->num_cntrs)
+		pmu_enable_counter(cci_pmu, i);
+}
+
+/*
  * Returns the number of programmable counters actually implemented
  * by the cci
  */
-- 
1.7.9.5

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#1316521 — [PATCH v6 10/12] arm-cci: CCI-500: Work around PMU counter writes

The CCI PMU driver sets the event counter to the half of the maximum
value(2^31) it can count before we start the counters via
pmu_event_set_period(). This is done to give us the best chance to
handle the overflow interrupt, taking care of extreme interrupt latencies.

However, CCI-500 comes with advanced power saving schemes, which
disables the clock to the event counters unless the counters are enabled to
count (PMCR.CEN). This prevents the driver from writing the period to the
counters before starting them.  Also, there is no way we can reset the
individual event counter to 0 (PMCR.RST resets all the counters, losing
their current readings). However the value of the counter is preserved and
could be read back, when the counters are not enabled.

So we cannot reliably use the counters and compute the number of events
generated during the sampling period since we don't have the value of the
counter at start.

This patch works around this issue by changing writes to the counter
with the following steps.

 1) Disable all the counters (remembering any counters which were enabled)
 2) Enable the PMU, now that all the counters are disabled.

 For each counter to be programmed, repeat steps 3-7
 3) Save the current event and program the target counter to count an
    invalid event, which by spec is guaranteed to not-generate any events.
 4) Enable the target counter.
 5) Write to the target counter.
 6) Disable the target counter
 7) Restore the event back on the target counter.

 8) Disable the PMU
 9) Restore the status of the all the counters

Cc: Punit Agrawal <punit.agrawal@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@arm.com>
---
 drivers/bus/arm-cci.c |   68 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)

diff --git a/drivers/bus/arm-cci.c b/drivers/bus/arm-cci.c
index 4e68593..69a8a61 100644
--- a/drivers/bus/arm-cci.c
+++ b/drivers/bus/arm-cci.c
@@ -890,6 +890,73 @@ static void pmu_write_counters(struct cci_pmu *cci_pmu, unsigned long *mask)
 		__pmu_write_counters(cci_pmu, mask);
 }
 
+#ifdef CONFIG_ARM_CCI500_PMU
+
+/*
+ * CCI-500 has advanced power saving policies, which could gate the
+ * clocks to the PMU counters, which makes the writes to them ineffective.
+ * The only way to write to those counters is when the global counters
+ * are enabled and the particular counter is enabled.
+ *
+ * So we do the following :
+ *
+ * 1) Disable all the PMU counters, saving their current state
+ * 2) Enable the global PMU profiling, now that all counters are
+ *    disabled.
+ *
+ * For each counter to be programmed, repeat steps 3-7:
+ *
+ * 3) Write an invalid event code to the event control register for the
+      counter, so that the counters are not modified.
+ * 4) Enable the counter control for the counter.
+ * 5) Set the counter value
+ * 6) Restore the event in the target counter
+ * 7) Disable the counter
+ *
+ * 8) Disable the global PMU.
+ * 9) Restore the status of the rest of the counters.
+ *
+ * We choose an event code which has very little chances of getting
+ * assigned a valid code for step(2). We use the highest possible
+ * event code (0x1f) for the master interface 0.
+ */
+#define CCI500_INVALID_EVENT	((CCI500_PORT_M0 << CCI500_PMU_EVENT_SOURCE_SHIFT) | \
+				 (CCI500_PMU_EVENT_CODE_MASK << CCI500_PMU_EVENT_CODE_SHIFT))
+static void cci500_pmu_write_counters(struct cci_pmu *cci_pmu, unsigned long *mask)
+{
+	int i;
+	DECLARE_BITMAP(saved_mask, cci_pmu->num_cntrs);
+
+	bitmap_zero(saved_mask, cci_pmu->num_cntrs);
+	pmu_save_counters(cci_pmu, saved_mask);
+
+	/*
+	 * Now that all the counters are disabled, we can safely turn the PMU on,
+	 * without syncing the status of the counters
+	 */
+	__cci_pmu_enable(cci_pmu, CCI_CNTRS_NOSYNC);
+
+	for_each_set_bit(i, mask, cci_pmu->num_cntrs) {
+		struct perf_event *event = cci_pmu->hw_events.events[i];
+
+		if (WARN_ON(!event))
+			continue;
+
+		pmu_set_event(cci_pmu, i, CCI500_INVALID_EVENT);
+		pmu_enable_counter(cci_pmu, i);
+		pmu_write_counter(cci_pmu,
+				  (u32)local64_read(&event->hw.prev_count), i);
+		pmu_disable_counter(cci_pmu, i);
+		pmu_set_event(cci_pmu, i, event->hw.config_base);
+	}
+
+	__cci_pmu_disable();
+
+	pmu_restore_counters(cci_pmu, saved_mask);
+}
+
+#endif	/* CONFIG_ARM_CCI500_PMU */
+
 static u64 pmu_event_update(struct perf_event *event)
 {
 	struct hw_perf_event *hwc = &event->hw;
@@ -1474,6 +1541,7 @@ static struct cci_pmu_model cci_pmu_models[] = {
 			},
 		},
 		.validate_hw_event = cci500_validate_hw_event,
+		.write_counters	= cci500_pmu_write_counters,
 	},
 #endif
 };
-- 
1.7.9.5

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