regmap-irq: Add get_irq_reg() callback

Replace the internal sub_irq_reg() function with a public callback
that drivers can use when they have more complex register layouts.
The default implementation is regmap_irq_get_irq_reg_linear(), used
if the chip doesn't provide its own callback.
Signed-off-by: Aidan MacDonald <aidanmacdonald.0x0@gmail.com>
Link: https://lore.kernel.org/r/20220623211420.918875-12-aidanmacdonald.0x0@gmail.comSigned-off-by: Mark Brown <broonie@kernel.org>

include/linux/regmap.h

@@ -1440,6 +1440,8 @@ struct regmap_irq_sub_irq_map {
 	unsigned int *offset;
 };
 
+struct regmap_irq_chip_data;
+
 /**
  * struct regmap_irq_chip - Description of a generic regmap irq_chip.
  *
@@ -1531,6 +1533,13 @@ struct regmap_irq_sub_irq_map {
  *		     and configure virt regs. Deprecated, use @set_type_config
  *		     callback and config registers instead.
  * @set_type_config: Callback used for configuring irq types.
+ * @get_irq_reg: Callback for mapping (base register, index) pairs to register
+ *		 addresses. The base register will be one of @status_base,
+ *		 @mask_base, etc., @main_status, or any of @config_base.
+ *		 The index will be in the range [0, num_main_regs[ for the
+ *		 main status base, [0, num_type_settings[ for any config
+ *		 register base, and [0, num_regs[ for any other base.
+ *		 If unspecified then regmap_irq_get_irq_reg_linear() is used.
  * @irq_drv_data:    Driver specific IRQ data which is passed as parameter when
  *		     driver specific pre/post interrupt handler is called.
  *
@@ -1585,11 +1594,13 @@ struct regmap_irq_chip {
 			     unsigned long hwirq, int reg);
 	int (*set_type_config)(unsigned int **buf, unsigned int type,
 			       const struct regmap_irq *irq_data, int idx);
+	unsigned int (*get_irq_reg)(struct regmap_irq_chip_data *data,
+				    unsigned int base, int index);
 	void *irq_drv_data;
 };
 
-struct regmap_irq_chip_data;
-
+unsigned int regmap_irq_get_irq_reg_linear(struct regmap_irq_chip_data *data,
+					   unsigned int base, int index);
 int regmap_irq_set_type_config_simple(unsigned int **buf, unsigned int type,
 				      const struct regmap_irq *irq_data, int idx);