s3c-fb: CPUFREQ frequency scaling support

Add support for CPU frequency scaling in the S3C24XX video driver.

Signed-off-by: Simtec Linux Team <linux@simtec.co.uk>
Signed-off-by: Ben Dooks <ben@simtec.co.uk>
Cc: Dave Jones <davej@codemonkey.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 70 insertions, 2 deletions

diff --git a/drivers/video/s3c2410fb.c b/drivers/video/s3c2410fb.c
index b0b4513ba537..7da0027e2409 100644
--- a/drivers/video/s3c2410fb.c
+++ b/drivers/video/s3c2410fb.c
@@ -24,6 +24,7 @@
 #include <linux/interrupt.h>
 #include <linux/platform_device.h>
 #include <linux/clk.h>
+#include <linux/cpufreq.h>
 
 #include <asm/io.h>
 #include <asm/div64.h>
@@ -89,7 +90,7 @@ static void s3c2410fb_set_lcdaddr(struct fb_info *info)
 static unsigned int s3c2410fb_calc_pixclk(struct s3c2410fb_info *fbi,
                                           unsigned long pixclk)
 {
-        unsigned long clk = clk_get_rate(fbi->clk);
+        unsigned long clk = fbi->clk_rate;
         unsigned long long div;
 
         /* pixclk is in picoseconds, our clock is in Hz
@@ -758,6 +759,57 @@ static irqreturn_t s3c2410fb_irq(int irq, void *dev_id)
         return IRQ_HANDLED;
 }
 
+#ifdef CONFIG_CPU_FREQ
+
+static int s3c2410fb_cpufreq_transition(struct notifier_block *nb,
+                                        unsigned long val, void *data)
+{
+        struct cpufreq_freqs *freqs = data;
+        struct s3c2410fb_info *info;
+        struct fb_info *fbinfo;
+        long delta_f;
+
+        info = container_of(nb, struct s3c2410fb_info, freq_transition);
+        fbinfo = platform_get_drvdata(to_platform_device(info->dev));
+
+        /* work out change, <0 for speed-up */
+        delta_f = info->clk_rate - clk_get_rate(info->clk);
+
+        if ((val == CPUFREQ_POSTCHANGE && delta_f > 0) ||
+            (val == CPUFREQ_PRECHANGE && delta_f < 0)) {
+                info->clk_rate = clk_get_rate(info->clk);
+                s3c2410fb_activate_var(fbinfo);
+        }
+
+        return 0;
+}
+
+static inline int s3c2410fb_cpufreq_register(struct s3c2410fb_info *info)
+{
+        info->freq_transition.notifier_call = s3c2410fb_cpufreq_transition;
+
+        return cpufreq_register_notifier(&info->freq_transition,
+                                         CPUFREQ_TRANSITION_NOTIFIER);
+}
+
+static inline void s3c2410fb_cpufreq_deregister(struct s3c2410fb_info *info)
+{
+        cpufreq_unregister_notifier(&info->freq_transition,
+                                    CPUFREQ_TRANSITION_NOTIFIER);
+}
+
+#else
+static inline int s3c2410fb_cpufreq_register(struct s3c2410fb_info *info)
+{
+        return 0;
+}
+
+static inline void s3c2410fb_cpufreq_deregister(struct s3c2410fb_info *info)
+{
+}
+#endif
+
+
 static char driver_name[] = "s3c2410fb";
 
 static int __init s3c24xxfb_probe(struct platform_device *pdev,
@@ -875,6 +927,8 @@ static int __init s3c24xxfb_probe(struct platform_device *pdev,
 
         msleep(1);
 
+        info->clk_rate = clk_get_rate(info->clk);
+
         /* find maximum required memory size for display */
         for (i = 0; i < mach_info->num_displays; i++) {
                 unsigned long smem_len = mach_info->displays[i].xres;
@@ -904,11 +958,17 @@ static int __init s3c24xxfb_probe(struct platform_device *pdev,
 
         s3c2410fb_check_var(&fbinfo->var, fbinfo);
 
+        ret = s3c2410fb_cpufreq_register(info);
+        if (ret < 0) {
+                dev_err(&pdev->dev, "Failed to register cpufreq\n");
+                goto free_video_memory;
+        }
+
         ret = register_framebuffer(fbinfo);
         if (ret < 0) {
                 printk(KERN_ERR "Failed to register framebuffer device: %d\n",
                         ret);
-                goto free_video_memory;
+                goto free_cpufreq;
         }
 
         /* create device files */
@@ -922,6 +982,8 @@ static int __init s3c24xxfb_probe(struct platform_device *pdev,
 
         return 0;
 
+ free_cpufreq:
+        s3c2410fb_cpufreq_deregister(info);
 free_video_memory:
         s3c2410fb_unmap_video_memory(fbinfo);
 release_clock:
@@ -961,6 +1023,7 @@ static int s3c2410fb_remove(struct platform_device *pdev)
         int irq;
 
         unregister_framebuffer(fbinfo);
+        s3c2410fb_cpufreq_deregister(info);
 
         s3c2410fb_lcd_enable(info, 0);
         msleep(1);
diff --git a/drivers/video/s3c2410fb.h b/drivers/video/s3c2410fb.h
index 9a6ba3e9d1b8..47a17bd23011 100644
--- a/drivers/video/s3c2410fb.h
+++ b/drivers/video/s3c2410fb.h
@@ -29,8 +29,13 @@ struct s3c2410fb_info {
         enum s3c_drv_type       drv_type;
         struct s3c2410fb_hw     regs;
 
+        unsigned long           clk_rate;
         unsigned int            palette_ready;
 
+#ifdef CONFIG_CPU_FREQ
+        struct notifier_block   freq_transition;
+#endif
+
         /* keep these registers in case we need to re-write palette */
         u32                     palette_buffer[256];
         u32                     pseudo_pal[16];