mfd: twl-core: Add initial DT support for twl4030/twl6030

Add initial device-tree support for twl familly chips.
The current version is missing the regulator entries due
to the lack of DT regulator bindings for the moment.
Only the simple sub-modules that do not depend on
platform_data information can be initialized properly.

Add irqdomain support.

Add documentation for the Texas Instruments TWL Integrated Chip.

Signed-off-by: Benoit Cousson <[e-mail]>
Cc: Balaji T K <[e-mail]>
Cc: Graeme Gregory <[e-mail]>
Signed-off-by: Samuel Ortiz <[e-mail]>
Acked-by: Rob Herring <[e-mail]>
[[e-mail]: Fix IRQ_DOMAIN dependency in kconfig]
Cc: Grant Likely <[e-mail]>

Documentation/devicetree/bindings/mfd/twl-familly.txt

···
+Texas Instruments TWL family
+
+The TWLs are Integrated Power Management Chips.
+Some version might contain much more analog function like
+USB transceiver or Audio amplifier.
+These chips are connected to an i2c bus.
+
+
+Required properties:
+- compatible : Must be "ti,twl4030";
+  For Integrated power-management/audio CODEC device used in OMAP3
+  based boards
+- compatible : Must be "ti,twl6030";
+  For Integrated power-management used in OMAP4 based boards
+- interrupts : This i2c device has an IRQ line connected to the main SoC
+- interrupt-controller : Since the twl support several interrupts internally,
+  it is considered as an interrupt controller cascaded to the SoC one.
+- #interrupt-cells = <1>;
+- interrupt-parent : The parent interrupt controller.
+
+Optional node:
+- Child nodes contain in the twl. The twl family is made of several variants
+  that support a different number of features.
+  The children nodes will thus depend of the capability of the variant.
+
+
+Example:
+/*
+ * Integrated Power Management Chip
+ * http://www.ti.com/lit/ds/symlink/twl6030.pdf
+ */
+twl@48 {
+    compatible = "ti,twl6030";
+    reg = <0x48>;
+    interrupts = <39>; /* IRQ_SYS_1N cascaded to gic */
+    interrupt-controller;
+    #interrupt-cells = <1>;
+    interrupt-parent = <&gic>;
+    #address-cells = <1>;
+    #size-cells = <0>;
+
+    twl_rtc {
+        compatible = "ti,twl_rtc";
+        interrupts = <11>;
+        reg = <0>;
+    };
+};

drivers/mfd/Kconfig

···
 
 config TWL4030_CORE
 	bool "Texas Instruments TWL4030/TWL5030/TWL6030/TPS659x0 Support"
-	depends on I2C=y && GENERIC_HARDIRQS
+	depends on I2C=y && GENERIC_HARDIRQS && IRQ_DOMAIN
 	help
 	  Say yes here if you have TWL4030 / TWL6030 family chip on your board.
 	  This core driver provides register access and IRQ handling

drivers/mfd/twl-core.c

···
 #include <linux/platform_device.h>
 #include <linux/clk.h>
 #include <linux/err.h>
+#include <linux/device.h>
+#include <linux/of.h>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+#include <linux/irqdomain.h>
 
 #include <linux/regulator/machine.h>
 
···
 #define SUB_CHIP_ID3 3
 
 #define TWL_MODULE_LAST TWL4030_MODULE_LAST
+
+#define TWL4030_NR_IRQS    8
+#define TWL6030_NR_IRQS    20
 
 /* Base Address defns for twl4030_map[] */
 
···
 
 static struct twl_client twl_modules[TWL_NUM_SLAVES];
 
+static struct irq_domain domain;
 
 /* mapping the module id to slave id and base address */
 struct twl_mapping {
···
 	int				status;
 	unsigned			i;
 	struct twl4030_platform_data	*pdata = client->dev.platform_data;
+	struct device_node		*node = client->dev.of_node;
 	u8 temp;
 	int ret = 0;
+	int nr_irqs = TWL4030_NR_IRQS;
+
+	if ((id->driver_data) & TWL6030_CLASS)
+		nr_irqs = TWL6030_NR_IRQS;
+
+	if (node && !pdata) {
+		/*
+		 * XXX: Temporary pdata until the information is correctly
+		 * retrieved by every TWL modules from DT.
+		 */
+		pdata = devm_kzalloc(&client->dev,
+				     sizeof(struct twl4030_platform_data),
+				     GFP_KERNEL);
+		if (!pdata)
+			return -ENOMEM;
+	}
 
 	if (!pdata) {
 		dev_dbg(&client->dev, "no platform data?\n");
 		return -EINVAL;
 	}
+
+	status = irq_alloc_descs(-1, pdata->irq_base, nr_irqs, 0);
+	if (IS_ERR_VALUE(status)) {
+		dev_err(&client->dev, "Fail to allocate IRQ descs\n");
+		return status;
+	}
+
+	pdata->irq_base = status;
+	pdata->irq_end = pdata->irq_base + nr_irqs;
+
+	domain.irq_base = pdata->irq_base;
+	domain.nr_irq = nr_irqs;
+#ifdef CONFIG_OF_IRQ
+	domain.of_node = of_node_get(node);
+	domain.ops = &irq_domain_simple_ops;
+#endif
+	irq_domain_add(&domain);
 
 	if (i2c_check_functionality(client->adapter, I2C_FUNC_I2C) == 0) {
 		dev_dbg(&client->dev, "can't talk I2C?\n");
···
 		twl_i2c_write_u8(TWL4030_MODULE_INTBR, temp, REG_GPPUPDCTR1);
 	}
 
-	status = add_children(pdata, id->driver_data);
+#ifdef CONFIG_OF_DEVICE
+	if (node)
+		status = of_platform_populate(node, NULL, NULL, &client->dev);
+	else
+#endif
+		status = add_children(pdata, id->driver_data);
+
 fail:
 	if (status < 0)
 		twl_remove(client);