regmap: regmap-irq: Add main status register support

There is bunch of devices with multiple logical blocks which
can generate interrupts. It's not a rare case that the interrupt
reason registers are arranged so that there is own status/ack/mask
register for each logical block. In some devices there is also a
'main interrupt register(s)' which can indicate what sub blocks
have interrupts pending.

When such a device is connected via slow bus like i2c the main
part of interrupt handling latency can be caused by bus accesses.
On systems where it is expected that only one (or few) sub blocks
have active interrupts we can reduce the latency by only reading
the main register and those sub registers which have active
interrupts. Support this with regmap-irq for simple cases where
main register does not require acking or masking.

Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

1 files changed, 31 insertions, 0 deletions

diff --git a/include/linux/regmap.h b/include/linux/regmap.h
index 1781b6cb793c..daeec7dbd65c 100644
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -1131,11 +1131,37 @@ struct regmap_irq {
 		.reg_offset = (_id) / (_reg_bits),	\
 	}
 
+#define REGMAP_IRQ_MAIN_REG_OFFSET(arr)				\
+	{ .num_regs = ARRAY_SIZE((arr)), .offset = &(arr)[0] }
+
+struct regmap_irq_sub_irq_map {
+	unsigned int num_regs;
+	unsigned int *offset;
+};
+
 /**
  * struct regmap_irq_chip - Description of a generic regmap irq_chip.
  *
  * @name:        Descriptive name for IRQ controller.
  *
+ * @main_status: Base main status register address. For chips which have
+ *		 interrupts arranged in separate sub-irq blocks with own IRQ
+ *		 registers and which have a main IRQ registers indicating
+ *		 sub-irq blocks with unhandled interrupts. For such chips fill
+ *		 sub-irq register information in status_base, mask_base and
+ *		 ack_base.
+ * @num_main_status_bits: Should be given to chips where number of meaningfull
+ *			  main status bits differs from num_regs.
+ * @sub_reg_offsets: arrays of mappings from main register bits to sub irq
+ *		     registers. First item in array describes the registers
+ *		     for first main status bit. Second array for second bit etc.
+ *		     Offset is given as sub register status offset to
+ *		     status_base. Should contain num_regs arrays.
+ *		     Can be provided for chips with more complex mapping than
+ *		     1.st bit to 1.st sub-reg, 2.nd bit to 2.nd sub-reg, ...
+ * @num_main_regs: Number of 'main status' irq registers for chips which have
+ *		   main_status set.
+ *
  * @status_base: Base status register address.
  * @mask_base:   Base mask register address.
  * @mask_writeonly: Base mask register is write only.
@@ -1181,6 +1207,11 @@ struct regmap_irq {
 struct regmap_irq_chip {
 	const char *name;
 
+	unsigned int main_status;
+	unsigned int num_main_status_bits;
+	struct regmap_irq_sub_irq_map *sub_reg_offsets;
+	int num_main_regs;
+
 	unsigned int status_base;
 	unsigned int mask_base;
 	unsigned int unmask_base;