[media] v4l: omap4iss: Replace outdated OMAP4 control pad API with syscon

The omap4_ctrl_pad_readl and omap4_ctrl_pad_writel functions have been
removed by commit efde2346 but are still used by the OMAP4 ISS
driver, resulting in a compilation breakage:

drivers/staging/media/omap4iss/iss_csiphy.c: In function 'omap4iss_csiphy_config':
drivers/staging/media/omap4iss/iss_csiphy.c:167:2: error: implicit declaration of function 'omap4_ctrl_pad_writel' [-Werror=implicit-function-declaration]
  omap4_ctrl_pad_writel(cam_rx_ctrl,

Fix the problem by using the syscon API to reaplace the control pad API.
Lookup the syscon instance by compatible name for now as the OMAP4 ISS
driver doesn't support DT yet.

Fixes: efde2346 ("ARM: OMAP4+: control: remove support for legacy pad read/write")
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Acked-by: Sakari Alius <sakari.ailus@iki.fi>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>

drivers/staging/media/omap4iss/Kconfig

@@ -2,6 +2,7 @@ config VIDEO_OMAP4
 	bool "OMAP 4 Camera support"
 	depends on VIDEO_V4L2=y && VIDEO_V4L2_SUBDEV_API && I2C=y && ARCH_OMAP4
 	depends on HAS_DMA
+	select MFD_SYSCON
 	select VIDEOBUF2_DMA_CONTIG
 	---help---
 	  Driver for an OMAP 4 ISS controller.

drivers/staging/media/omap4iss/iss.c

@@ -17,6 +17,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/i2c.h>
 #include <linux/interrupt.h>
+#include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
@@ -1386,6 +1387,16 @@ static int iss_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, iss);
 
+	/*
+	 * TODO: When implementing DT support switch to syscon regmap lookup by
+	 * phandle.
+	 */
+	iss->syscon = syscon_regmap_lookup_by_compatible("syscon");
+	if (IS_ERR(iss->syscon)) {
+		ret = PTR_ERR(iss->syscon);
+		goto error;
+	}
+
 	/* Clocks */
 	ret = iss_map_mem_resource(pdev, iss, OMAP4_ISS_MEM_TOP);
 	if (ret < 0)

drivers/staging/media/omap4iss/iss.h

@@ -29,6 +29,8 @@
 #include "iss_ipipe.h"
 #include "iss_resizer.h"
 
+struct regmap;
+
 #define to_iss_device(ptr_module)				\
 	container_of(ptr_module, struct iss_device, ptr_module)
 #define to_device(ptr_module)						\
@@ -79,6 +81,7 @@ struct iss_reg {
 
 /*
  * struct iss_device - ISS device structure.
+ * @syscon: Regmap for the syscon register space
  * @crashed: Bitmask of crashed entities (indexed by entity ID)
  */
 struct iss_device {
@@ -93,6 +96,7 @@ struct iss_device {
 
 	struct resource *res[OMAP4_ISS_MEM_LAST];
 	void __iomem *regs[OMAP4_ISS_MEM_LAST];
+	struct regmap *syscon;
 
 	u64 raw_dmamask;
 

drivers/staging/media/omap4iss/iss_csiphy.c

@@ -13,6 +13,7 @@
 
 #include <linux/delay.h>
 #include <linux/device.h>
+#include <linux/regmap.h>
 
 #include "../../../../arch/arm/mach-omap2/control.h"
 
@@ -140,9 +141,11 @@ int omap4iss_csiphy_config(struct iss_device *iss,
 	 * - bit [18] : CSIPHY1 CTRLCLK enable
 	 * - bit [17:16] : CSIPHY1 config: 00 d-phy, 01/10 ccp2
 	 */
-	cam_rx_ctrl = omap4_ctrl_pad_readl(
-			OMAP4_CTRL_MODULE_PAD_CORE_CONTROL_CAMERA_RX);
-
+	/*
+	 * TODO: When implementing DT support specify the CONTROL_CAMERA_RX
+	 * register offset in the syscon property instead of hardcoding it.
+	 */
+	regmap_read(iss->syscon, 0x68, &cam_rx_ctrl);
 
 	if (subdevs->interface == ISS_INTERFACE_CSI2A_PHY1) {
 		cam_rx_ctrl &= ~(OMAP4_CAMERARX_CSI21_LANEENABLE_MASK |
@@ -166,8 +169,7 @@ int omap4iss_csiphy_config(struct iss_device *iss,
 		cam_rx_ctrl |= OMAP4_CAMERARX_CSI22_CTRLCLKEN_MASK;
 	}
 
-	omap4_ctrl_pad_writel(cam_rx_ctrl,
-		 OMAP4_CTRL_MODULE_PAD_CORE_CONTROL_CAMERA_RX);
+	regmap_write(iss->syscon, 0x68, cam_rx_ctrl);
 
 	/* Reset used lane count */
 	csi2->phy->used_data_lanes = 0;