powerpc/mpic: FSL MPIC error interrupt support.

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@freescale.com>
Signed-off-by: Bogdan Hamciuc <bogdan.hamciuc@freescale.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>

4 files changed, 215 insertions, 2 deletions

diff --git a/arch/powerpc/sysdev/Makefile b/arch/powerpc/sysdev/Makefile
index 1bd7ecb24620..a57600b3a4e3 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 000000000000..b83f32562a37
--- /dev/null
+++ b/arch/powerpc/sysdev/fsl_mpic_err.c
@@ -0,0 +1,149 @@
+/*
+ * Copyright (C) 2012 Freescale Semiconductor, Inc.
+ *
+ * Author: Varun Sethi <varun.sethi@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 mpic_fsl_err_read(u32 __iomem *base, unsigned int err_reg)
+{
+	return in_be32(base + (err_reg >> 2));
+}
+
+static inline void mpic_fsl_err_write(u32 __iomem *base, u32 value)
+{
+	out_be32(base + (MPIC_ERR_INT_EIMR >> 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];
+
+	eimr = mpic_fsl_err_read(mpic->err_regs, MPIC_ERR_INT_EIMR);
+	eimr |= (1 << (31 - src));
+	mpic_fsl_err_write(mpic->err_regs, 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];
+
+	eimr = mpic_fsl_err_read(mpic->err_regs, MPIC_ERR_INT_EIMR);
+	eimr &= ~(1 << (31 - src));
+	mpic_fsl_err_write(mpic->err_regs, 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,
+};
+
+int 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 -ENOMEM;
+	}
+	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;
+
+	return 0;
+}
+
+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;
+	u32 eisr, eimr;
+	int errint;
+	unsigned int cascade_irq;
+
+	eisr = mpic_fsl_err_read(mpic->err_regs, MPIC_ERR_INT_EISR);
+	eimr = mpic_fsl_err_read(mpic->err_regs, MPIC_ERR_INT_EIMR);
+
+	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);
+			mpic_fsl_err_write(mpic->err_regs, eimr);
+		}
+		eisr &= ~(1 << (31 - errint));
+	}
+
+	return IRQ_HANDLED;
+}
+
+void mpic_err_int_init(struct mpic *mpic, irq_hw_number_t irqnum)
+{
+	unsigned int virq;
+	int ret;
+
+	virq = irq_create_mapping(mpic->irqhost, irqnum);
+	if (virq == NO_IRQ) {
+		pr_err("Error interrupt setup failed\n");
+		return;
+	}
+
+	/* Mask all error interrupts */
+	mpic_fsl_err_write(mpic->err_regs, ~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");
+}
diff --git a/arch/powerpc/sysdev/mpic.c b/arch/powerpc/sysdev/mpic.c
index 7e32db7e7b0d..9c6e535daad2 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 +1088,16 @@ 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;
+
+			*out_hwirq = mpic->err_int_vecs[intspec[3]];
+
 			break;
 		case 2:
 			if (intspec[0] >= ARRAY_SIZE(mpic->ipi_vecs))
@@ -1302,6 +1314,9 @@ 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;
+		int ret;
+
 		/*
 		 * Yes, Freescale really did put global registers in the
 		 * magic per-cpu area -- and they don't even show up in the
@@ -1309,6 +1324,29 @@ 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.
+		 *
+		 * Over here we reserve vector number space for error
+		 * interrupt vectors. This space is stolen from the
+		 * global vector number space, as in case of ipis
+		 * and timer interrupts.
+		 *
+		 * Available vector space = intvec_top - 12, where 12
+		 * is the number of vectors which have been consumed by
+		 * ipis and timer interrupts.
+		 */
+		if (version >= 0x401) {
+			ret = mpic_setup_error_int(mpic, intvec_top - 12);
+			if (ret)
+				return NULL;
+		}
 	}
 
 	/* Reset */
@@ -1474,6 +1512,10 @@ void __init mpic_init(struct mpic *mpic)
 			num_timers = 8;
 	}
 
+	/* FSL mpic error interrupt intialization */
+	if (mpic->flags & MPIC_FSL_HAS_EIMR)
+		mpic_err_int_init(mpic, MPIC_FSL_ERR_INT);
+
 	/* Initialize timers to our reserved vectors and mask them for now */
 	for (i = 0; i < num_timers; i++) {
 		unsigned int offset = mpic_tm_offset(mpic, i);
diff --git a/arch/powerpc/sysdev/mpic.h b/arch/powerpc/sysdev/mpic.h
index 13f3e8913a93..24bf07a63924 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 void mpic_err_int_init(struct mpic *mpic, irq_hw_number_t irqnum);
+extern int 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 void mpic_err_int_init(struct mpic *mpic, irq_hw_number_t irqnum)
+{
+	return;
+}
+
+static inline int mpic_setup_error_int(struct mpic *mpic, int intvec)
+{
+	return -1;
+}
+#endif
+
 #endif /* _POWERPC_SYSDEV_MPIC_H */