[PATCH 3/3 v2] powerpc/mpic: FSL MPIC error interrupt support.

Varun Sethi Varun.Sethi at freescale.com
Sun Jun 3 17:45:40 EST 2012


All SOC device error interrupts are muxed and delivered to the core as a single
MPIC error interrupt. Currently all the device drivers requiring access to device
errors have to register for the MPIC error interrupt as a shared interrupt.

With this patch we add interrupt demuxing capability in the mpic driver, allowing
device drivers to register for their individual error interrupts. This is achieved
by handling error interrupts in a cascaded fashion.

MPIC error interrupt is handled by the "error_int_handler", which subsequently demuxes
it using the EISR and delivers it to the respective drivers. 

The error interrupt capability is dependent on the MPIC EIMR register, which was
introduced in FSL MPIC version 4.1 (P4080 rev2). So, error interrupt demuxing capability
is dependent on the MPIC version and can be used for versions >= 4.1.

Signed-off-by: Varun Sethi <Varun.Sethi at freescale.com>
Signed-off-by: Bogdan Hamciuc <bogdan.hamciuc at freescale.com>
[In the initial version of the patch we were using handle_simple_irq
 as the handler for cascaded error interrupts, this resulted
 in issues in case of threaded isrs (with RT kernel). This issue was
 debugged by Bogdan and decision was taken to use the handle_level_irq
 handler]
---
 arch/powerpc/include/asm/mpic.h    |   17 ++++
 arch/powerpc/sysdev/Makefile       |    2 +-
 arch/powerpc/sysdev/fsl_mpic_err.c |  157 ++++++++++++++++++++++++++++++++++++
 arch/powerpc/sysdev/mpic.c         |   35 ++++++++-
 arch/powerpc/sysdev/mpic.h         |   22 +++++
 5 files changed, 231 insertions(+), 2 deletions(-)
 create mode 100644 arch/powerpc/sysdev/fsl_mpic_err.c

diff --git a/arch/powerpc/include/asm/mpic.h b/arch/powerpc/include/asm/mpic.h
index e14d35d..71b42b9 100644
--- a/arch/powerpc/include/asm/mpic.h
+++ b/arch/powerpc/include/asm/mpic.h
@@ -114,10 +114,17 @@
 #define MPIC_FSL_BRR1			0x00000
 #define 	MPIC_FSL_BRR1_VER			0x0000ffff
 
+/*
+ * Error interrupt registers
+ */
+
+
 #define MPIC_MAX_IRQ_SOURCES	2048
 #define MPIC_MAX_CPUS		32
 #define MPIC_MAX_ISU		32
 
+#define MPIC_MAX_ERR      32
+
 /*
  * Tsi108 implementation of MPIC has many differences from the original one
  */
@@ -270,6 +277,7 @@ struct mpic
 	struct irq_chip		hc_ipi;
 #endif
 	struct irq_chip		hc_tm;
+	struct irq_chip		hc_err;
 	const char		*name;
 	/* Flags */
 	unsigned int		flags;
@@ -283,6 +291,8 @@ struct mpic
 	/* vector numbers used for internal sources (ipi/timers) */
 	unsigned int		ipi_vecs[4];
 	unsigned int		timer_vecs[8];
+	/* vector numbers used for FSL MPIC error interrupts */
+	unsigned int		err_int_vecs[MPIC_MAX_ERR];
 
 	/* Spurious vector to program into unused sources */
 	unsigned int		spurious_vec;
@@ -306,6 +316,11 @@ struct mpic
 	struct mpic_reg_bank	cpuregs[MPIC_MAX_CPUS];
 	struct mpic_reg_bank	isus[MPIC_MAX_ISU];
 
+	/* ioremap'ed base for error interrupt registers */
+	u32 __iomem	*err_regs;
+	/* error interrupt config */
+	u32			err_int_config_done;
+
 	/* Protected sources */
 	unsigned long		*protected;
 
@@ -370,6 +385,8 @@ struct mpic
 #define MPIC_NO_RESET			0x00004000
 /* Freescale MPIC (compatible includes "fsl,mpic") */
 #define MPIC_FSL			0x00008000
+/* Freescale MPIC supports EIMR (error interrupt mask register)*/
+#define MPIC_FSL_HAS_EIMR		0x00010000
 
 /* MPIC HW modification ID */
 #define MPIC_REGSET_MASK		0xf0000000
diff --git a/arch/powerpc/sysdev/Makefile b/arch/powerpc/sysdev/Makefile
index 1bd7ecb..a57600b 100644
--- a/arch/powerpc/sysdev/Makefile
+++ b/arch/powerpc/sysdev/Makefile
@@ -15,7 +15,7 @@ obj-$(CONFIG_PPC_DCR_NATIVE)	+= dcr-low.o
 obj-$(CONFIG_PPC_PMI)		+= pmi.o
 obj-$(CONFIG_U3_DART)		+= dart_iommu.o
 obj-$(CONFIG_MMIO_NVRAM)	+= mmio_nvram.o
-obj-$(CONFIG_FSL_SOC)		+= fsl_soc.o
+obj-$(CONFIG_FSL_SOC)		+= fsl_soc.o fsl_mpic_err.o
 obj-$(CONFIG_FSL_PCI)		+= fsl_pci.o $(fsl-msi-obj-y)
 obj-$(CONFIG_FSL_PMC)		+= fsl_pmc.o
 obj-$(CONFIG_FSL_LBC)		+= fsl_lbc.o
diff --git a/arch/powerpc/sysdev/fsl_mpic_err.c b/arch/powerpc/sysdev/fsl_mpic_err.c
new file mode 100644
index 0000000..f2d28f2
--- /dev/null
+++ b/arch/powerpc/sysdev/fsl_mpic_err.c
@@ -0,0 +1,157 @@
+/*
+ * Copyright (C) 2012 Freescale Semiconductor, Inc.
+ *
+ * Author: Varun Sethi <varun.sethi at freescale.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; version 2 of the
+ * License.
+ *
+ */
+
+#include <linux/irq.h>
+#include <linux/smp.h>
+#include <linux/interrupt.h>
+
+#include <asm/io.h>
+#include <asm/irq.h>
+#include <asm/mpic.h>
+
+#include "mpic.h"
+
+#define MPIC_ERR_INT_BASE	0x3900
+#define MPIC_ERR_INT_EISR	0x0000
+#define MPIC_ERR_INT_EIMR	0x0010
+
+static inline u32 fsl_mpic_err_read(u32 __iomem *base, unsigned int err_reg)
+{
+	return in_be32(base + (err_reg >> 2));
+}
+
+static inline void fsl_mpic_err_write(u32 __iomem *base, unsigned int err_reg,
+				   u32 value)
+{
+	out_be32(base + (err_reg >> 2), value);
+}
+
+static void fsl_mpic_mask_err(struct irq_data *d)
+{
+	u32 eimr;
+	struct mpic *mpic = irq_data_get_irq_chip_data(d);
+	unsigned int src = virq_to_hw(d->irq) - mpic->err_int_vecs[0];
+	unsigned int err_reg_offset = MPIC_ERR_INT_EIMR;
+
+	eimr = fsl_mpic_err_read(mpic->err_regs, err_reg_offset);
+	eimr |= (1 << (31 - src));
+	fsl_mpic_err_write(mpic->err_regs, err_reg_offset, eimr);
+}
+
+static void fsl_mpic_unmask_err(struct irq_data *d)
+{
+	u32 eimr;
+	struct mpic *mpic = irq_data_get_irq_chip_data(d);
+	unsigned int src = virq_to_hw(d->irq) - mpic->err_int_vecs[0];
+	unsigned int err_reg_offset = MPIC_ERR_INT_EIMR;
+
+	eimr = fsl_mpic_err_read(mpic->err_regs, err_reg_offset);
+	eimr &= ~(1 << (31 - src));
+	fsl_mpic_err_write(mpic->err_regs, err_reg_offset, eimr);
+}
+
+static struct irq_chip fsl_mpic_err_chip = {
+	.irq_disable	= fsl_mpic_mask_err,
+	.irq_mask	= fsl_mpic_mask_err,
+	.irq_unmask	= fsl_mpic_unmask_err,
+};
+
+void mpic_setup_error_int(struct mpic *mpic, int intvec)
+{
+	int i;
+
+	mpic->err_regs = ioremap(mpic->paddr + MPIC_ERR_INT_BASE, 0x1000);
+	if (!mpic->err_regs) {
+		pr_err("could not map mpic error registers\n");
+		return;
+	}
+	mpic->hc_err = fsl_mpic_err_chip;
+	mpic->hc_err.name = mpic->name;
+	mpic->flags |= MPIC_FSL_HAS_EIMR;
+	/* allocate interrupt vectors for error interrupts */
+	for (i = MPIC_MAX_ERR - 1; i >= 0; i--)
+		mpic->err_int_vecs[i] = --intvec;
+
+}
+
+int mpic_map_error_int(struct mpic *mpic, unsigned int virq, irq_hw_number_t  hw)
+{
+	if ((mpic->flags & MPIC_FSL_HAS_EIMR) &&
+	    (hw >= mpic->err_int_vecs[0] &&
+	     hw <= mpic->err_int_vecs[MPIC_MAX_ERR - 1])) {
+		WARN_ON(mpic->flags & MPIC_SECONDARY);
+
+		pr_debug("mpic: mapping as Error Interrupt\n");
+		irq_set_chip_data(virq, mpic);
+		irq_set_chip_and_handler(virq, &mpic->hc_err,
+					 handle_level_irq);
+		return 1;
+	}
+
+	return 0;
+}
+
+static irqreturn_t fsl_error_int_handler(int irq, void *data)
+{
+	struct mpic *mpic = (struct mpic *) data;
+	unsigned int eisr_offset = MPIC_ERR_INT_EISR;
+	unsigned int eimr_offset = MPIC_ERR_INT_EIMR;
+	u32 eisr, eimr;
+	int errint;
+	unsigned int cascade_irq;
+
+	eisr = fsl_mpic_err_read(mpic->err_regs, eisr_offset);
+	eimr = fsl_mpic_err_read(mpic->err_regs, eimr_offset);
+
+	if (!(eisr & ~eimr))
+		return IRQ_NONE;
+
+	while (eisr) {
+		errint = __builtin_clz(eisr);
+		cascade_irq = irq_linear_revmap(mpic->irqhost,
+				 mpic->err_int_vecs[errint]);
+		WARN_ON(cascade_irq == NO_IRQ);
+		if (cascade_irq != NO_IRQ) {
+			generic_handle_irq(cascade_irq);
+		} else {
+			eimr |=  1 << (31 - errint);
+			fsl_mpic_err_write(mpic->err_regs, eimr_offset, eimr);
+		}
+		eisr &= ~(1 << (31 - errint));
+	}
+
+	return IRQ_HANDLED;
+}
+
+int mpic_err_int_init(struct mpic *mpic, irq_hw_number_t irqnum)
+{
+	unsigned int virq;
+	unsigned int offset = MPIC_ERR_INT_EIMR;
+	int ret;
+
+	virq = irq_create_mapping(mpic->irqhost, irqnum);
+	if (virq == NO_IRQ) {
+		pr_err("Error interrupt setup failed\n");
+		return -ENOSPC;
+	}
+
+	fsl_mpic_err_write(mpic->err_regs, offset, ~0);
+
+	ret = request_irq(virq, fsl_error_int_handler, IRQF_NO_THREAD,
+		    "mpic-error-int", mpic);
+	if (ret) {
+		pr_err("Failed to register error interrupt handler\n");
+		return ret;
+	}
+
+	return 0;
+}
diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index 61c7225..7002ef3 100644
--- a/arch/powerpc/sysdev/mpic.c
+++ b/arch/powerpc/sysdev/mpic.c
@@ -1026,6 +1026,9 @@ static int mpic_host_map(struct irq_domain *h, unsigned int virq,
 		return 0;
 	}
 
+	if (mpic_map_error_int(mpic, virq, hw))
+		return 0;
+
 	if (hw >= mpic->num_sources)
 		return -EINVAL;
 
@@ -1085,7 +1088,24 @@ static int mpic_host_xlate(struct irq_domain *h, struct device_node *ct,
 		 */
 		switch (intspec[2]) {
 		case 0:
-		case 1: /* no EISR/EIMR support for now, treat as shared IRQ */
+			break;
+		case 1:
+			if (!(mpic->flags & MPIC_FSL_HAS_EIMR))
+				break;
+
+			if (intspec[3] >= ARRAY_SIZE(mpic->err_int_vecs))
+				return -EINVAL;
+
+			if (!mpic->err_int_config_done) {
+				int ret;
+				ret = mpic_err_int_init(mpic, intspec[0]);
+				if (ret)
+					return ret;
+				mpic->err_int_config_done = 1;
+			}
+
+			*out_hwirq = mpic->err_int_vecs[intspec[3]];
+
 			break;
 		case 2:
 			if (intspec[0] >= ARRAY_SIZE(mpic->ipi_vecs))
@@ -1302,6 +1322,8 @@ struct mpic * __init mpic_alloc(struct device_node *node,
 	mpic_map(mpic, mpic->paddr, &mpic->tmregs, MPIC_INFO(TIMER_BASE), 0x1000);
 
 	if (mpic->flags & MPIC_FSL) {
+		u32 brr1, version;
+
 		/*
 		 * Yes, Freescale really did put global registers in the
 		 * magic per-cpu area -- and they don't even show up in the
@@ -1309,6 +1331,17 @@ struct mpic * __init mpic_alloc(struct device_node *node,
 		 */
 		mpic_map(mpic, mpic->paddr, &mpic->thiscpuregs,
 			 MPIC_CPU_THISBASE, 0x1000);
+
+		brr1 = _mpic_read(mpic->reg_type, &mpic->thiscpuregs,
+				MPIC_FSL_BRR1);
+		version = brr1 & MPIC_FSL_BRR1_VER;
+
+		/* Error interrupt mask register (EIMR) is required for
+		 * handling individual device error interrupts. EIMR
+		 * was added in MPIC version 4.1.
+		 */
+		if (version >= 0x401)
+			mpic_setup_error_int(mpic, intvec_top - 12);
 	}
 
 	/* Reset */
diff --git a/arch/powerpc/sysdev/mpic.h b/arch/powerpc/sysdev/mpic.h
index 13f3e89..1a6995a 100644
--- a/arch/powerpc/sysdev/mpic.h
+++ b/arch/powerpc/sysdev/mpic.h
@@ -40,4 +40,26 @@ extern int mpic_set_affinity(struct irq_data *d,
 			     const struct cpumask *cpumask, bool force);
 extern void mpic_reset_core(int cpu);
 
+#ifdef CONFIG_FSL_SOC
+extern int mpic_map_error_int(struct mpic *mpic, unsigned int virq, irq_hw_number_t  hw);
+extern int mpic_err_int_init(struct mpic *mpic, irq_hw_number_t irqnum);
+extern void mpic_setup_error_int(struct mpic *mpic, int intvec);
+#else
+static inline int mpic_map_error_int(struct mpic *mpic, unsigned int virq, irq_hw_number_t  hw)
+{
+	return 0;
+}
+
+
+static inline int mpic_err_int_init(struct mpic *mpic, irq_hw_number_t irqnum)
+{
+	return -1;
+}
+
+static inline void mpic_setup_error_int(struct mpic *mpic, int intvec)
+{
+	return;
+}
+#endif
+
 #endif /* _POWERPC_SYSDEV_MPIC_H */
-- 
1.7.2.2




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