sh: intc: IRQ auto-distribution support.

This implements support for hardware-managed IRQ balancing as implemented
by SH-X3 cores (presently only hooked up for SH7786, but can probably be
carried over to other SH-X3 cores, too).

CPUs need to specify their distribution register along with the mask
definitions, as these follow the same format. Peripheral IRQs that don't
opt out of balancing will be automatically distributed at the whim of the
hardware block, while each CPU needs to verify whether it is handling the
IRQ or not, especially before clearing the mask.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>

2 files changed, 159 insertions, 52 deletions

diff --git a/drivers/sh/Kconfig b/drivers/sh/Kconfig
index 22c3cda..a54de0b 100644
--- a/drivers/sh/Kconfig
+++ b/drivers/sh/Kconfig
@@ -11,3 +11,14 @@ config INTC_USERIMASK
 	  drivers that are using special priority levels.
 
 	  If in doubt, say N.
+
+config INTC_BALANCING
+	bool "Hardware IRQ balancing support"
+	depends on SMP && SUPERH && CPU_SUBTYPE_SH7786
+	help
+	  This enables support for IRQ auto-distribution mode on SH-X3
+	  SMP parts. All of the balancing and CPU wakeup decisions are
+	  taken care of automatically by hardware for distributed
+	  vectors.
+
+	  If in doubt, say N.
diff --git a/drivers/sh/intc.c b/drivers/sh/intc.c
index 77d10ac..dcb4c83 100644
--- a/drivers/sh/intc.c
+++ b/drivers/sh/intc.c
@@ -98,6 +98,9 @@ static DEFINE_SPINLOCK(vector_lock);
 static unsigned int intc_prio_level[NR_IRQS];	/* for now */
 static unsigned int default_prio_level = 2;	/* 2 - 16 */
 static unsigned long ack_handle[NR_IRQS];
+#ifdef CONFIG_INTC_BALANCING
+static unsigned long dist_handle[NR_IRQS];
+#endif
 
 static inline struct intc_desc_int *get_intc_desc(unsigned int irq)
 {
@@ -105,6 +108,47 @@ static inline struct intc_desc_int *get_intc_desc(unsigned int irq)
 	return container_of(chip, struct intc_desc_int, chip);
 }
 
+static unsigned long intc_phys_to_virt(struct intc_desc_int *d,
+				       unsigned long address)
+{
+	struct intc_window *window;
+	int k;
+
+	/* scan through physical windows and convert address */
+	for (k = 0; k < d->nr_windows; k++) {
+		window = d->window + k;
+
+		if (address < window->phys)
+			continue;
+
+		if (address >= (window->phys + window->size))
+			continue;
+
+		address -= window->phys;
+		address += (unsigned long)window->virt;
+
+		return address;
+	}
+
+	/* no windows defined, register must be 1:1 mapped virt:phys */
+	return address;
+}
+
+static unsigned int intc_get_reg(struct intc_desc_int *d, unsigned long address)
+{
+	unsigned int k;
+
+	address = intc_phys_to_virt(d, address);
+
+	for (k = 0; k < d->nr_reg; k++) {
+		if (d->reg[k] == address)
+			return k;
+	}
+
+	BUG();
+	return 0;
+}
+
 static inline unsigned int set_field(unsigned int value,
 				     unsigned int field_value,
 				     unsigned int handle)
@@ -238,6 +282,85 @@ static void (*intc_disable_fns[])(unsigned long addr,
 	[MODE_PCLR_REG] = intc_mode_field,
 };
 
+#ifdef CONFIG_INTC_BALANCING
+static inline void intc_balancing_enable(unsigned int irq)
+{
+	struct intc_desc_int *d = get_intc_desc(irq);
+	unsigned long handle = dist_handle[irq];
+	unsigned long addr;
+
+	if (irq_balancing_disabled(irq) || !handle)
+		return;
+
+	addr = INTC_REG(d, _INTC_ADDR_D(handle), 0);
+	intc_reg_fns[_INTC_FN(handle)](addr, handle, 1);
+}
+
+static inline void intc_balancing_disable(unsigned int irq)
+{
+	struct intc_desc_int *d = get_intc_desc(irq);
+	unsigned long handle = dist_handle[irq];
+	unsigned long addr;
+
+	if (irq_balancing_disabled(irq) || !handle)
+		return;
+
+	addr = INTC_REG(d, _INTC_ADDR_D(handle), 0);
+	intc_reg_fns[_INTC_FN(handle)](addr, handle, 0);
+}
+
+static unsigned int intc_dist_data(struct intc_desc *desc,
+				   struct intc_desc_int *d,
+				   intc_enum enum_id)
+{
+	struct intc_mask_reg *mr = desc->hw.mask_regs;
+	unsigned int i, j, fn, mode;
+	unsigned long reg_e, reg_d;
+
+	for (i = 0; mr && enum_id && i < desc->hw.nr_mask_regs; i++) {
+		mr = desc->hw.mask_regs + i;
+
+		/*
+		 * Skip this entry if there's no auto-distribution
+		 * register associated with it.
+		 */
+		if (!mr->dist_reg)
+			continue;
+
+		for (j = 0; j < ARRAY_SIZE(mr->enum_ids); j++) {
+			if (mr->enum_ids[j] != enum_id)
+				continue;
+
+			fn = REG_FN_MODIFY_BASE;
+			mode = MODE_ENABLE_REG;
+			reg_e = mr->dist_reg;
+			reg_d = mr->dist_reg;
+
+			fn += (mr->reg_width >> 3) - 1;
+			return _INTC_MK(fn, mode,
+					intc_get_reg(d, reg_e),
+					intc_get_reg(d, reg_d),
+					1,
+					(mr->reg_width - 1) - j);
+		}
+	}
+
+	/*
+	 * It's possible we've gotten here with no distribution options
+	 * available for the IRQ in question, so we just skip over those.
+	 */
+	return 0;
+}
+#else
+static inline void intc_balancing_enable(unsigned int irq)
+{
+}
+
+static inline void intc_balancing_disable(unsigned int irq)
+{
+}
+#endif
+
 static inline void _intc_enable(unsigned int irq, unsigned long handle)
 {
 	struct intc_desc_int *d = get_intc_desc(irq);
@@ -253,6 +376,8 @@ static inline void _intc_enable(unsigned int irq, unsigned long handle)
 		intc_enable_fns[_INTC_MODE(handle)](addr, handle, intc_reg_fns\
 						    [_INTC_FN(handle)], irq);
 	}
+
+	intc_balancing_enable(irq);
 }
 
 static void intc_enable(unsigned int irq)
@@ -263,10 +388,12 @@ static void intc_enable(unsigned int irq)
 static void intc_disable(unsigned int irq)
 {
 	struct intc_desc_int *d = get_intc_desc(irq);
-	unsigned long handle = (unsigned long) get_irq_chip_data(irq);
+	unsigned long handle = (unsigned long)get_irq_chip_data(irq);
 	unsigned long addr;
 	unsigned int cpu;
 
+	intc_balancing_disable(irq);
+
 	for (cpu = 0; cpu < SMP_NR(d, _INTC_ADDR_D(handle)); cpu++) {
 #ifdef CONFIG_SMP
 		if (!cpumask_test_cpu(cpu, irq_to_desc(irq)->affinity))
@@ -345,8 +472,7 @@ static void intc_mask_ack(unsigned int irq)
 
 	intc_disable(irq);
 
-	/* read register and write zero only to the assocaited bit */
-
+	/* read register and write zero only to the associated bit */
 	if (handle) {
 		addr = INTC_REG(d, _INTC_ADDR_D(handle), 0);
 		switch (_INTC_FN(handle)) {
@@ -375,7 +501,8 @@ static struct intc_handle_int *intc_find_irq(struct intc_handle_int *hp,
 {
 	int i;
 
-	/* this doesn't scale well, but...
+	/*
+	 * this doesn't scale well, but...
 	 *
 	 * this function should only be used for cerain uncommon
 	 * operations such as intc_set_priority() and intc_set_sense()
@@ -386,7 +513,6 @@ static struct intc_handle_int *intc_find_irq(struct intc_handle_int *hp,
 	 * memory footprint down is to make sure the array is sorted
 	 * and then perform a bisect to lookup the irq.
 	 */
-
 	for (i = 0; i < nr_hp; i++) {
 		if ((hp + i)->irq != irq)
 			continue;
@@ -417,7 +543,6 @@ int intc_set_priority(unsigned int irq, unsigned int prio)
 		 * primary masking method is using intc_prio_level[irq]
 		 * priority level will be set during next enable()
 		 */
-
 		if (_INTC_FN(ihp->handle) != REG_FN_ERR)
 			_intc_enable(irq, ihp->handle);
 	}
@@ -456,48 +581,6 @@ static int intc_set_sense(unsigned int irq, unsigned int type)
 	return 0;
 }
 
-static unsigned long intc_phys_to_virt(struct intc_desc_int *d,
-				       unsigned long address)
-{
-	struct intc_window *window;
-	int k;
-
-	/* scan through physical windows and convert address */
-	for (k = 0; k < d->nr_windows; k++) {
-		window = d->window + k;
-
-		if (address < window->phys)
-			continue;
-
-		if (address >= (window->phys + window->size))
-			continue;
-
-		address -= window->phys;
-		address += (unsigned long)window->virt;
-
-		return address;
-	}
-
-	/* no windows defined, register must be 1:1 mapped virt:phys */
-	return address;
-}
-
-static unsigned int __init intc_get_reg(struct intc_desc_int *d,
-					unsigned long address)
-{
-	unsigned int k;
-
-	address = intc_phys_to_virt(d, address);
-
-	for (k = 0; k < d->nr_reg; k++) {
-		if (d->reg[k] == address)
-			return k;
-	}
-
-	BUG();
-	return 0;
-}
-
 static intc_enum __init intc_grp_id(struct intc_desc *desc,
 				    intc_enum enum_id)
 {
@@ -755,13 +838,14 @@ static void __init intc_register_irq(struct intc_desc *desc,
 	 */
 	set_bit(irq, intc_irq_map);
 
-	/* Prefer single interrupt source bitmap over other combinations:
+	/*
+	 * Prefer single interrupt source bitmap over other combinations:
+	 *
 	 * 1. bitmap, single interrupt source
 	 * 2. priority, single interrupt source
 	 * 3. bitmap, multiple interrupt sources (groups)
 	 * 4. priority, multiple interrupt sources (groups)
 	 */
-
 	data[0] = intc_mask_data(desc, d, enum_id, 0);
 	data[1] = intc_prio_data(desc, d, enum_id, 0);
 
@@ -786,7 +870,8 @@ static void __init intc_register_irq(struct intc_desc *desc,
 				      handle_level_irq, "level");
 	set_irq_chip_data(irq, (void *)data[primary]);
 
-	/* set priority level
+	/*
+	 * set priority level
 	 * - this needs to be at least 2 for 5-bit priorities on 7780
 	 */
 	intc_prio_level[irq] = default_prio_level;
@@ -806,7 +891,6 @@ static void __init intc_register_irq(struct intc_desc *desc,
 			 * only secondary priority should access registers, so
 			 * set _INTC_FN(h) = REG_FN_ERR for intc_set_priority()
 			 */
-
 			hp->handle &= ~_INTC_MK(0x0f, 0, 0, 0, 0, 0);
 			hp->handle |= _INTC_MK(REG_FN_ERR, 0, 0, 0, 0, 0);
 		}
@@ -827,6 +911,11 @@ static void __init intc_register_irq(struct intc_desc *desc,
 	if (desc->hw.ack_regs)
 		ack_handle[irq] = intc_ack_data(desc, d, enum_id);
 
+#ifdef CONFIG_INTC_BALANCING
+	if (desc->hw.mask_regs)
+		dist_handle[irq] = intc_dist_data(desc, d, enum_id);
+#endif
+
 #ifdef CONFIG_ARM
 	set_irq_flags(irq, IRQF_VALID); /* Enable IRQ on ARM systems */
 #endif
@@ -892,6 +981,10 @@ int __init register_intc_controller(struct intc_desc *desc)
 	}
 
 	d->nr_reg = hw->mask_regs ? hw->nr_mask_regs * 2 : 0;
+#ifdef CONFIG_INTC_BALANCING
+	if (d->nr_reg)
+		d->nr_reg += hw->nr_mask_regs;
+#endif
 	d->nr_reg += hw->prio_regs ? hw->nr_prio_regs * 2 : 0;
 	d->nr_reg += hw->sense_regs ? hw->nr_sense_regs : 0;
 	d->nr_reg += hw->ack_regs ? hw->nr_ack_regs : 0;
@@ -912,6 +1005,9 @@ int __init register_intc_controller(struct intc_desc *desc)
 			smp = IS_SMP(hw->mask_regs[i]);
 			k += save_reg(d, k, hw->mask_regs[i].set_reg, smp);
 			k += save_reg(d, k, hw->mask_regs[i].clr_reg, smp);
+#ifdef CONFIG_INTC_BALANCING
+			k += save_reg(d, k, hw->mask_regs[i].dist_reg, 0);
+#endif
 		}
 	}