video:sunxi:disp: add version ioctl

* introduce some version macros to the ioctl header.
* introduce a new versioning ioctl.
* pr_info the version on load.
* verbosely warn when user application is not using the version
  ioctl before doing anything else with /dev/disp
* verbosely warn about the bumpy road ahead, and point to the
  wiki when doing so.

Signed-off-by: Luc Verhaegen <libv@skynet.be>

Documentation/sunxi/disp/version.c

@@ -0,0 +1,67 @@
+/*
+ * Simple example to ease users of /dev/disp into using the new but mandatory
+ * versioning handshake ioctl. No license or copyright claims made.
+ *
+ * Use
+ *   gcc -Wall -I../../../include -o disp_version version.c
+ * to compile this.
+ *
+ * Author: Luc Verhaegen <libv@skynet.be>
+ */
+
+#include <stdio.h>
+#include <fcntl.h>
+#include <sys/ioctl.h>
+#include <errno.h>
+#include <string.h>
+#include <asm/types.h>
+
+#include <video/sunxi_disp_ioctl.h>
+
+int
+main(int argc, char *argv[])
+{
+	int fd = open("/dev/disp", O_RDWR);
+	int ret, tmp, width, height;
+
+	if (fd == -1) {
+                fprintf(stderr, "Error: Failed to open /dev/mali: %s\n",
+                       strerror(errno));
+                return errno;
+        }
+
+	tmp = SUNXI_DISP_VERSION;
+	ret = ioctl(fd, DISP_CMD_VERSION, &tmp);
+        if (ret < 0) {
+                fprintf(stderr, "Error: ioctl(VERSION) failed: %s\n",
+                       strerror(-ret));
+                return ret;
+        }
+
+	printf("disp kernel module version is %d.%d\n",
+	       ret >> 16, ret & 0xFFFF);
+
+	tmp = 0;
+	ret = ioctl(fd, DISP_CMD_SCN_GET_WIDTH, &tmp);
+        if (ret) {
+                fprintf(stderr, "Error: ioctl(SCN_GET_WIDTH) failed: %s\n",
+                       strerror(ret));
+                return ret;
+        }
+
+	width = ret;
+
+	tmp = 0;
+	ret = ioctl(fd, DISP_CMD_SCN_GET_HEIGHT, &tmp);
+        if (ret) {
+                fprintf(stderr, "Error: ioctl(SCN_GET_HEIGHT) failed: %s\n",
+                       strerror(ret));
+                return ret;
+        }
+
+	height = ret;
+
+	printf("DISP dimensions are %dx%d\n", width, height);
+
+	return 0;
+}

drivers/video/sunxi/disp/dev_disp.c

@@ -1,6 +1,7 @@
 /*
  * copyright (c) 2007-2012 Allwinner Technology Co., Ltd.
  * copyright (c) 2007-2012 Danling <danliang@allwinnertech.com>
+ * copyright (c) 2012 Luc Verhaegen <libv@skynet.be>
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as
@@ -387,7 +388,7 @@ disp_mem_release(int sel)
 
 }
 
-int disp_mmap(struct file *file, struct vm_area_struct *vma)
+int disp_mmap(struct file *filp, struct vm_area_struct *vma)
 {
 	// - PAGE_OFFSET;
 	unsigned long physics = g_disp_mm[g_disp_mm_sel].mem_start;
@@ -401,23 +402,58 @@ int disp_mmap(struct file *file, struct vm_area_struct *vma)
 	return 0;
 }
 
-int disp_open(struct inode *inode, struct file *file)
+/*
+ *
+ */
+struct dev_disp_data {
+	/* Version of the user of /dev/disp */
+#define SUNXI_DISP_VERSION_PENDING -1
+#define SUNXI_DISP_VERSION_SKIPPED -2
+	int version;
+};
+
+int disp_open(struct inode *inode, struct file *filp)
 {
+	struct dev_disp_data *data =
+		kmalloc(sizeof(struct dev_disp_data), GFP_KERNEL);
+	static bool warned;
+
+	if (!data)
+		return -ENOMEM;
+
+	data->version = SUNXI_DISP_VERSION_PENDING;
+
+	filp->private_data = data;
+
+	if (!warned) {
+		pr_warn("Warning: this sunxi disp driver will see significant "
+			"redesign.\n");
+		pr_warn("Applications using /dev/disp directly will break.\n");
+		pr_warn("For more information visit: "
+			"http://linux-sunxi.org/Sunxi_disp_driver\n");
+		warned = true;
+	}
+
 	return 0;
 }
 
-int disp_release(struct inode *inode, struct file *file)
+int disp_release(struct inode *inode, struct file *filp)
 {
+	struct dev_disp_data *data = filp->private_data;
+
+	kfree(data);
+	filp->private_data = NULL;
+
 	return 0;
 }
 
-ssize_t disp_read(struct file *file, char __user *buf, size_t count,
+ssize_t disp_read(struct file *filp, char __user *buf, size_t count,
 		  loff_t *ppos)
 {
 	return 0;
 }
 
-ssize_t disp_write(struct file *file, const char __user *buf, size_t count,
+ssize_t disp_write(struct file *filp, const char __user *buf, size_t count,
 		   loff_t *ppos)
 {
 	return 0;
@@ -467,6 +503,9 @@ static int __devinit disp_probe(struct platform_device *pdev)
 	__inf("PIO base 0x%08x\n", info->base_pioc);
 	__inf("PWM base 0x%08x\n", info->base_pwm);
 
+	pr_info("sunxi disp driver loaded (/dev/disp api %d.%d)\n",
+		SUNXI_DISP_VERSION_MAJOR, SUNXI_DISP_VERSION_MINOR);
+
 	return 0;
 }
 
@@ -605,8 +644,9 @@ disp_shutdown(struct platform_device *pdev)
 	}
 }
 
-long disp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
+long disp_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 {
+	struct dev_disp_data *filp_data = filp->private_data;
 	unsigned long karg[4];
 	unsigned long ubuffer[4] = { 0 };
 	__s32 ret = 0;
@@ -622,6 +662,39 @@ long disp_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	ubuffer[2] = (*(unsigned long *)(karg + 2));
 	ubuffer[3] = (*(unsigned long *)(karg + 3));
 
+	/* Verify version handshake first. */
+	if (filp_data->version == SUNXI_DISP_VERSION_PENDING) {
+		if (cmd == DISP_CMD_VERSION) {
+			int version = *((int *) karg);
+
+			if (version < 0) {
+				pr_err("disp: process %d (%s) provided an "
+				       "invalid version.\n",
+				       current->pid, current->comm);
+				filp_data->version = SUNXI_DISP_VERSION_SKIPPED;
+				return -EINVAL;
+			}
+
+			if (version != SUNXI_DISP_VERSION)
+				pr_warn("disp: process %d (%s) has a different "
+				       "version: %d.%d (vs. %d.%d)\n",
+					current->pid, current->comm,
+					SUNXI_DISP_VERSION_MAJOR_GET(version),
+					SUNXI_DISP_VERSION_MINOR_GET(version),
+					SUNXI_DISP_VERSION_MAJOR,
+					SUNXI_DISP_VERSION_MINOR);
+
+			/* Add compatibility checks here */
+
+			filp_data->version = version;
+			return SUNXI_DISP_VERSION;
+		} else {
+			pr_err("disp: process %d (%s) has skipped the version "
+			       "handshake.\n", current->pid, current->comm);
+			filp_data->version = SUNXI_DISP_VERSION_SKIPPED;
+		}
+	}
+
 	if (cmd < DISP_CMD_FB_REQUEST) {
 		if ((ubuffer[0] != 0) && (ubuffer[0] != 1)) {
 			__wrn("para err in disp_ioctl, cmd = 0x%x,"

include/video/sunxi_disp_ioctl.h

@@ -22,6 +22,14 @@
 
 #define __bool signed char
 
+/* for tracking the ioctls API/ABI */
+#define SUNXI_DISP_VERSION_MAJOR 1
+#define SUNXI_DISP_VERSION_MINOR 0
+
+#define SUNXI_DISP_VERSION ((SUNXI_DISP_VERSION_MAJOR << 16) | SUNXI_DISP_VERSION_MINOR)
+#define SUNXI_DISP_VERSION_MAJOR_GET(x) (((x) >> 16) & 0x7FFF)
+#define SUNXI_DISP_VERSION_MINOR_GET(x) ((x) & 0xFFFF)
+
 typedef struct {
 	__u8 alpha;
 	__u8 red;
@@ -622,7 +630,7 @@ typedef struct {
 
 typedef enum tag_DISP_CMD {
 	/* ----disp global---- */
-	DISP_CMD_RESERVE0 = 0x00,
+	DISP_CMD_VERSION = 0x00,
 	DISP_CMD_RESERVE1 = 0x01,
 	/* fail when the value is 0x02 in linux,why??? */
 	DISP_CMD_SET_BKCOLOR = 0x3f,