drm/pl111: Add a debugfs node to dump our registers.

While debugging an X11 display failure, I wanted to see where we were
actually scanning out from.  This is probably generally useful to
others that might be working on this device.

v2: Fix uint32_t sparse warning.
Signed-off-by: Eric Anholt <eric@anholt.net>
Link: http://patchwork.freedesktop.org/patch/msgid/20170518005640.10310-1-eric@anholt.net
Reviewed-by: Linus Walleij <linus.walleij@linaro.org> (v1)

drivers/gpu/drm/pl111/Makefile

@@ -2,4 +2,6 @@ pl111_drm-y +=	pl111_connector.o \
 		pl111_display.o \
 		pl111_drv.o
 
+pl111_drm-$(CONFIG_DEBUG_FS) += pl111_debugfs.o
+
 obj-$(CONFIG_DRM_PL111) += pl111_drm.o

drivers/gpu/drm/pl111/pl111_debugfs.c

+/*
+ *  Copyright © 2017 Broadcom
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/amba/clcd-regs.h>
+#include <linux/seq_file.h>
+#include <drm/drm_debugfs.h>
+#include <drm/drmP.h>
+#include "pl111_drm.h"
+
+#define REGDEF(reg) { reg, #reg }
+static const struct {
+	u32 reg;
+	const char *name;
+} pl111_reg_defs[] = {
+	REGDEF(CLCD_TIM0),
+	REGDEF(CLCD_TIM1),
+	REGDEF(CLCD_TIM2),
+	REGDEF(CLCD_TIM3),
+	REGDEF(CLCD_UBAS),
+	REGDEF(CLCD_PL111_CNTL),
+	REGDEF(CLCD_PL111_IENB),
+};
+
+int pl111_debugfs_regs(struct seq_file *m, void *unused)
+{
+	struct drm_info_node *node = (struct drm_info_node *)m->private;
+	struct drm_device *dev = node->minor->dev;
+	struct pl111_drm_dev_private *priv = dev->dev_private;
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(pl111_reg_defs); i++) {
+		seq_printf(m, "%s (0x%04x): 0x%08x\n",
+			   pl111_reg_defs[i].name, pl111_reg_defs[i].reg,
+			   readl(priv->regs + pl111_reg_defs[i].reg));
+	}
+
+	return 0;
+}
+
+static const struct drm_info_list pl111_debugfs_list[] = {
+	{"regs", pl111_debugfs_regs, 0},
+};
+
+int
+pl111_debugfs_init(struct drm_minor *minor)
+{
+	return drm_debugfs_create_files(pl111_debugfs_list,
+					ARRAY_SIZE(pl111_debugfs_list),
+					minor->debugfs_root, minor);
+}

drivers/gpu/drm/pl111/pl111_drm.h

@@ -25,6 +25,8 @@
 
 #define CLCD_IRQ_NEXTBASE_UPDATE BIT(2)
 
+struct drm_minor;
+
 struct pl111_drm_connector {
 	struct drm_connector connector;
 	struct drm_panel *panel;
@@ -60,5 +62,6 @@ int pl111_encoder_init(struct drm_device *dev);
 int pl111_dumb_create(struct drm_file *file_priv,
 		      struct drm_device *dev,
 		      struct drm_mode_create_dumb *args);
+int pl111_debugfs_init(struct drm_minor *minor);
 
 #endif /* _PL111_DRM_H_ */

drivers/gpu/drm/pl111/pl111_drv.c

@@ -173,6 +173,10 @@ static struct drm_driver pl111_drm_driver = {
 	.gem_prime_import_sg_table = drm_gem_cma_prime_import_sg_table,
 	.gem_prime_export = drm_gem_prime_export,
 	.gem_prime_get_sg_table	= drm_gem_cma_prime_get_sg_table,
+
+#if defined(CONFIG_DEBUG_FS)
+	.debugfs_init = pl111_debugfs_init,
+#endif
 };
 
 #ifdef CONFIG_ARM_AMBA