video: tegra: Implement EDID query

This change implements the TEGRA_DC_EXT_CONTROL_GET_OUTPUT_EDID ioctl in
the dc_ext interface.

It first adds a way for the tegra dc EDID module to export EDID data
safely, without the risk of reading an incomplete or corrupted EDID in
the presence of hotplug, by moving the actual data to a substructure
with a lifetime maintained by a kref.  Then, that support is plumbed
through the hdmi block (which is currently the only way to get at the
EDID) and out to userspace.

Signed-off-by: Robert Morell <rmorell@nvidia.com>

Bug 817119

Original-Change-Id: I78cd170e15322011b428cb71ffad2c0c3ea058ac
Reviewed-on: http://git-master/r/49127
Reviewed-by: Rohan Somvanshi <rsomvanshi@nvidia.com>
Tested-by: Rohan Somvanshi <rsomvanshi@nvidia.com>

Rebase-Id: Rafafc0a6fbacda5494b12162ad99a8c70ceeb2e0

1 files changed, 111 insertions, 39 deletions

diff --git a/drivers/video/tegra/dc/edid.c b/drivers/video/tegra/dc/edid.c
index 055cea3a11fe..7b23c60bc57e 100644
--- a/drivers/video/tegra/dc/edid.c
+++ b/drivers/video/tegra/dc/edid.c
@@ -26,33 +26,52 @@
 
 #include "edid.h"
 
+struct tegra_edid_pvt {
+	struct kref			refcnt;
+	struct tegra_edid_hdmi_eld	eld;
+	bool				support_stereo;
+	/* Note: dc_edid must remain the last member */
+	struct tegra_dc_edid		dc_edid;
+};
+
 struct tegra_edid {
 	struct i2c_client	*client;
 	struct i2c_board_info	info;
 	int			bus;
 
-	u8			*data;
-	unsigned		len;
-	u8			support_stereo;
-	struct tegra_edid_hdmi_eld		eld;
+	struct tegra_edid_pvt	*data;
+
+	struct mutex		lock;
 };
 
 #if defined(DEBUG) || defined(CONFIG_DEBUG_FS)
 static int tegra_edid_show(struct seq_file *s, void *unused)
 {
 	struct tegra_edid *edid = s->private;
+	struct tegra_dc_edid *data;
+	u8 *buf;
 	int i;
 
-	for (i = 0; i < edid->len; i++) {
+	data = tegra_edid_get_data(edid);
+	if (!data) {
+		seq_printf(s, "No EDID\n");
+		return 0;
+	}
+
+	buf = data->buf;
+
+	for (i = 0; i < data->len; i++) {
 		if (i % 16 == 0)
 			seq_printf(s, "edid[%03x] =", i);
 
-		seq_printf(s, " %02x", edid->data[i]);
+		seq_printf(s, " %02x", buf[i]);
 
 		if (i % 16 == 15)
 			seq_printf(s, "\n");
 	}
 
+	tegra_edid_put_data(data);
+
 	return 0;
 }
 #endif
@@ -165,9 +184,10 @@ int tegra_edid_read_block(struct tegra_edid *edid, int block, u8 *data)
 	return 0;
 }
 
-int tegra_edid_parse_ext_block(u8 *raw, int idx, struct tegra_edid *edid)
+int tegra_edid_parse_ext_block(const u8 *raw, int idx,
+			       struct tegra_edid_pvt *edid)
 {
-	u8 *ptr;
+	const u8 *ptr;
 	u8 tmp;
 	u8 code;
 	int len;
@@ -300,45 +320,64 @@ int tegra_edid_mode_support_stereo(struct fb_videomode *mode)
 	return 0;
 }
 
+static void data_release(struct kref *ref)
+{
+	struct tegra_edid_pvt *data =
+		container_of(ref, struct tegra_edid_pvt, refcnt);
+	vfree(data);
+}
+
 int tegra_edid_get_monspecs(struct tegra_edid *edid, struct fb_monspecs *specs)
 {
 	int i;
 	int j;
 	int ret;
 	int extension_blocks;
+	struct tegra_edid_pvt *new_data, *old_data;
+	u8 *data;
+
+	new_data = vmalloc(SZ_32K + sizeof(struct tegra_edid_pvt));
+	if (!new_data)
+		return -ENOMEM;
 
-	edid->support_stereo = 0;
+	kref_init(&new_data->refcnt);
 
-	ret = tegra_edid_read_block(edid, 0, edid->data);
+	new_data->support_stereo = 0;
+
+	data = new_data->dc_edid.buf;
+
+	ret = tegra_edid_read_block(edid, 0, data);
 	if (ret)
-		return ret;
+		goto fail;
 
 	memset(specs, 0x0, sizeof(struct fb_monspecs));
-	memset(&edid->eld, 0x0, sizeof(struct tegra_edid_hdmi_eld));
-	fb_edid_to_monspecs(edid->data, specs);
-	if (specs->modedb == NULL)
-		return -EINVAL;
-	memcpy(edid->eld.monitor_name, specs->monitor, sizeof(specs->monitor));
-	edid->eld.mnl = strlen(edid->eld.monitor_name) + 1;
-	edid->eld.product_id[0] = edid->data[0x8];
-	edid->eld.product_id[1] = edid->data[0x9];
-	edid->eld.manufacture_id[0] = edid->data[0xA];
-	edid->eld.manufacture_id[1] = edid->data[0xB];
-
-	extension_blocks = edid->data[0x7e];
+	memset(&new_data->eld, 0x0, sizeof(new_data->eld));
+	fb_edid_to_monspecs(data, specs);
+	if (specs->modedb == NULL) {
+		ret = -EINVAL;
+		goto fail;
+	}
+	memcpy(new_data->eld.monitor_name, specs->monitor, sizeof(specs->monitor));
+	new_data->eld.mnl = strlen(new_data->eld.monitor_name) + 1;
+	new_data->eld.product_id[0] = data[0x8];
+	new_data->eld.product_id[1] = data[0x9];
+	new_data->eld.manufacture_id[0] = data[0xA];
+	new_data->eld.manufacture_id[1] = data[0xB];
+
+	extension_blocks = data[0x7e];
 
 	for (i = 1; i <= extension_blocks; i++) {
-		ret = tegra_edid_read_block(edid, i, edid->data + i * 128);
+		ret = tegra_edid_read_block(edid, i, data + i * 128);
 		if (ret < 0)
 			break;
 
-		if (edid->data[i * 128] == 0x2) {
-			fb_edid_add_monspecs(edid->data + i * 128, specs);
+		if (data[i * 128] == 0x2) {
+			fb_edid_add_monspecs(data + i * 128, specs);
 
-			tegra_edid_parse_ext_block(edid->data + i * 128,
-					edid->data[i * 128 + 2], edid);
+			tegra_edid_parse_ext_block(data + i * 128,
+					data[i * 128 + 2], new_data);
 
-			if (edid->support_stereo) {
+			if (new_data->support_stereo) {
 				for (j = 0; j < specs->modedb_len; j++) {
 					if (tegra_edid_mode_support_stereo(
 						&specs->modedb[j]))
@@ -349,18 +388,30 @@ int tegra_edid_get_monspecs(struct tegra_edid *edid, struct fb_monspecs *specs)
 		}
 	}
 
-	edid->len = i * 128;
+	new_data->dc_edid.len = i * 128;
+
+	mutex_lock(&edid->lock);
+	old_data = edid->data;
+	edid->data = new_data;
+	mutex_unlock(&edid->lock);
+
+	if (old_data)
+		kref_put(&old_data->refcnt, data_release);
 
 	tegra_edid_dump(edid);
 	return 0;
+
+fail:
+	vfree(new_data);
+	return ret;
 }
 
 int tegra_edid_get_eld(struct tegra_edid *edid, struct tegra_edid_hdmi_eld *elddata)
 {
-	if (!elddata)
+	if (!elddata || !edid->data)
 		return -EFAULT;
 
-	memcpy(elddata,&edid->eld,sizeof(struct tegra_edid_hdmi_eld));
+	memcpy(elddata,&edid->data->eld,sizeof(struct tegra_edid_hdmi_eld));
 
 	return 0;
 }
@@ -375,11 +426,7 @@ struct tegra_edid *tegra_edid_create(int bus)
 	if (!edid)
 		return ERR_PTR(-ENOMEM);
 
-	edid->data = vmalloc(SZ_32K);
-	if (!edid->data) {
-		err = -ENOMEM;
-		goto free_edid;
-	}
+	mutex_init(&edid->lock);
 	strlcpy(edid->info.type, "tegra_edid", sizeof(edid->info.type));
 	edid->bus = bus;
 	edid->info.addr = 0x50;
@@ -406,7 +453,6 @@ struct tegra_edid *tegra_edid_create(int bus)
 	return edid;
 
 free_edid:
-	vfree(edid->data);
 	kfree(edid);
 
 	return ERR_PTR(err);
@@ -415,10 +461,36 @@ free_edid:
 void tegra_edid_destroy(struct tegra_edid *edid)
 {
 	i2c_release_client(edid->client);
-	vfree(edid->data);
+	if (edid->data)
+		kref_put(&edid->data->refcnt, data_release);
 	kfree(edid);
 }
 
+struct tegra_dc_edid *tegra_edid_get_data(struct tegra_edid *edid)
+{
+	struct tegra_edid_pvt *data;
+
+	mutex_lock(&edid->lock);
+	data = edid->data;
+	if (data)
+		kref_get(&data->refcnt);
+	mutex_unlock(&edid->lock);
+
+	return data ? &data->dc_edid : NULL;
+}
+
+void tegra_edid_put_data(struct tegra_dc_edid *data)
+{
+	struct tegra_edid_pvt *pvt;
+
+	if (!data)
+		return;
+
+	pvt = container_of(data, struct tegra_edid_pvt, dc_edid);
+
+	kref_put(&pvt->refcnt, data_release);
+}
+
 static const struct i2c_device_id tegra_edid_id[] = {
         { "tegra_edid", 0 },
         { }