kernel: MIPS: perf: ath79: Fix perfcount IRQ assignment

Currently it's not possible to use perf on ath79 due to genirq flags
mismatch happening on static virtual IRQ 13 which is used for
performance counters hardware IRQ 5.

On TP-Link Archer C7v5:

           CPU0
  2:          0      MIPS   2  ath9k
  4:        318      MIPS   4  19000000.eth
  7:      55034      MIPS   7  timer
  8:       1236      MISC   3  ttyS0
 12:          0      INTC   1  ehci_hcd:usb1
 13:          0  gpio-ath79   2  keys
 14:          0  gpio-ath79   5  keys
 15:         31  AR724X PCI    1  ath10k_pci

 $ perf top
 genirq: Flags mismatch irq 13. 00014c83 (mips_perf_pmu) vs. 00002003 (keys)

On TP-Link Archer C7v4:

         CPU0
  4:          0      MIPS   4  19000000.eth
  5:       7135      MIPS   5  1a000000.eth
  7:      98379      MIPS   7  timer
  8:         30      MISC   3  ttyS0
 12:      90028      INTC   0  ath9k
 13:       5520      INTC   1  ehci_hcd:usb1
 14:       4623      INTC   2  ehci_hcd:usb2
 15:      32844  AR724X PCI    1  ath10k_pci
 16:          0  gpio-ath79  16  keys
 23:          0  gpio-ath79  23  keys

 $ perf top
 genirq: Flags mismatch irq 13. 00014c80 (mips_perf_pmu) vs. 00000080 (ehci_hcd:usb1)

This problem is happening, because currently statically assigned virtual
IRQ 13 for performance counters is not claimed during the initialization
of MIPS PMU during the bootup, so the IRQ subsystem doesn't know, that
this interrupt isn't available for further use.

So this patch fixes the issue by simply booking hardware IRQ 5 for MIPS PMU.

Signed-off-by: Petr Štetiar <ynezz@true.cz>

1 files changed, 117 insertions, 0 deletions

diff --git a/target/linux/generic/pending-4.19/103-MIPS-perf-ath79-Fix-perfcount-IRQ-assignment.patch b/target/linux/generic/pending-4.19/103-MIPS-perf-ath79-Fix-perfcount-IRQ-assignment.patch
new file mode 100644
index 0000000000..9e97f8af2d
--- /dev/null
+++ b/target/linux/generic/pending-4.19/103-MIPS-perf-ath79-Fix-perfcount-IRQ-assignment.patch
@@ -0,0 +1,117 @@
+From 852a88f35f4b7e5ebb717fed3c3a3330d5ad4336 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Petr=20=C5=A0tetiar?= <ynezz@true.cz>
+Date: Wed, 10 Apr 2019 16:43:27 +0200
+Subject: [PATCH v2] MIPS: perf: ath79: Fix perfcount IRQ assignment
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+Currently it's not possible to use perf on ath79 due to genirq flags
+mismatch happening on static virtual IRQ 13 which is used for
+performance counters hardware IRQ 5.
+
+On TP-Link Archer C7v5:
+
+           CPU0
+  2:          0      MIPS   2  ath9k
+  4:        318      MIPS   4  19000000.eth
+  7:      55034      MIPS   7  timer
+  8:       1236      MISC   3  ttyS0
+ 12:          0      INTC   1  ehci_hcd:usb1
+ 13:          0  gpio-ath79   2  keys
+ 14:          0  gpio-ath79   5  keys
+ 15:         31  AR724X PCI    1  ath10k_pci
+
+ $ perf top
+ genirq: Flags mismatch irq 13. 00014c83 (mips_perf_pmu) vs. 00002003 (keys)
+
+On TP-Link Archer C7v4:
+
+         CPU0
+  4:          0      MIPS   4  19000000.eth
+  5:       7135      MIPS   5  1a000000.eth
+  7:      98379      MIPS   7  timer
+  8:         30      MISC   3  ttyS0
+ 12:      90028      INTC   0  ath9k
+ 13:       5520      INTC   1  ehci_hcd:usb1
+ 14:       4623      INTC   2  ehci_hcd:usb2
+ 15:      32844  AR724X PCI    1  ath10k_pci
+ 16:          0  gpio-ath79  16  keys
+ 23:          0  gpio-ath79  23  keys
+
+ $ perf top
+ genirq: Flags mismatch irq 13. 00014c80 (mips_perf_pmu) vs. 00000080 (ehci_hcd:usb1)
+
+This problem is happening, because currently statically assigned virtual
+IRQ 13 for performance counters is not claimed during the initialization
+of MIPS PMU during the bootup, so the IRQ subsystem doesn't know, that
+this interrupt isn't available for further use.
+
+So this patch fixes the issue by simply booking hardware IRQ 5 for MIPS PMU.
+
+Tested-by: Kevin 'ldir' Darbyshire-Bryant <ldir@darbyshire-bryant.me.uk>
+Signed-off-by: Petr Štetiar <ynezz@true.cz>
+---
+
+Changes since v1:
+
+ I've incorporated two comments which I've received on IRC from blogic and
+ I've also reworded the commit message to match the changes in v2 of this
+ patch.
+
+  * use actual hardware perfcount IRQ 5 instead of the virtual IRQ 13
+  * dropped the CONFIG_PERF_EVENTS ifdef around irq_create_mapping
+
+ arch/mips/ath79/setup.c          |  6 ------
+ drivers/irqchip/irq-ath79-misc.c | 11 +++++++++++
+ 2 files changed, 11 insertions(+), 6 deletions(-)
+
+diff --git a/arch/mips/ath79/setup.c b/arch/mips/ath79/setup.c
+index 4a70c5d..25a5789 100644
+--- a/arch/mips/ath79/setup.c
++++ b/arch/mips/ath79/setup.c
+@@ -210,12 +210,6 @@ const char *get_system_type(void)
+ 	return ath79_sys_type;
+ }
+ 
+-int get_c0_perfcount_int(void)
+-{
+-	return ATH79_MISC_IRQ(5);
+-}
+-EXPORT_SYMBOL_GPL(get_c0_perfcount_int);
+-
+ unsigned int get_c0_compare_int(void)
+ {
+ 	return CP0_LEGACY_COMPARE_IRQ;
+diff --git a/drivers/irqchip/irq-ath79-misc.c b/drivers/irqchip/irq-ath79-misc.c
+index aa72907..0390603 100644
+--- a/drivers/irqchip/irq-ath79-misc.c
++++ b/drivers/irqchip/irq-ath79-misc.c
+@@ -22,6 +22,15 @@
+ #define AR71XX_RESET_REG_MISC_INT_ENABLE	4
+ 
+ #define ATH79_MISC_IRQ_COUNT			32
++#define ATH79_MISC_PERF_IRQ			5
++
++static int ath79_perfcount_irq;
++
++int get_c0_perfcount_int(void)
++{
++	return ath79_perfcount_irq;
++}
++EXPORT_SYMBOL_GPL(get_c0_perfcount_int);
+ 
+ static void ath79_misc_irq_handler(struct irq_desc *desc)
+ {
+@@ -113,6 +122,8 @@ static void __init ath79_misc_intc_domain_init(
+ {
+ 	void __iomem *base = domain->host_data;
+ 
++	ath79_perfcount_irq = irq_create_mapping(domain, ATH79_MISC_PERF_IRQ);
++
+ 	/* Disable and clear all interrupts */
+ 	__raw_writel(0, base + AR71XX_RESET_REG_MISC_INT_ENABLE);
+ 	__raw_writel(0, base + AR71XX_RESET_REG_MISC_INT_STATUS);
+-- 
+1.9.1
+