[PATCH] Rewritten backlight infrastructure for portable Apple computers

This patch contains a total rewrite of the backlight infrastructure for
portable Apple computers.  Backward compatibility is retained.  A sysfs
interface allows userland to control the brightness with more steps than
before.  Userland is allowed to upload a brightness curve for different
monitors, similar to Mac OS X.

[akpm@osdl.org: add needed exports]
Signed-off-by: Michael Hanselmann <linux-kernel@hansmi.ch>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Richard Purdie <rpurdie@rpsys.net>
Cc: "Antonino A. Daplas" <adaplas@pol.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

3 files changed, 121 insertions, 167 deletions

diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 91a6e04d9741..52f5659534f4 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -32,6 +32,7 @@
 #include <linux/delay.h>
 #include <linux/kprobes.h>
 #include <linux/kexec.h>
+#include <linux/backlight.h>
 
 #include <asm/kdebug.h>
 #include <asm/pgtable.h>
@@ -105,10 +106,18 @@ int die(const char *str, struct pt_regs *regs, long err)
         spin_lock_irq(&die_lock);
         bust_spinlocks(1);
 #ifdef CONFIG_PMAC_BACKLIGHT
-        if (machine_is(powermac)) {
-                set_backlight_enable(1);
-                set_backlight_level(BACKLIGHT_MAX);
+        mutex_lock(&pmac_backlight_mutex);
+        if (machine_is(powermac) && pmac_backlight) {
+                struct backlight_properties *props;
+
+                down(&pmac_backlight->sem);
+                props = pmac_backlight->props;
+                props->brightness = props->max_brightness;
+                props->power = FB_BLANK_UNBLANK;
+                props->update_status(pmac_backlight);
+                up(&pmac_backlight->sem);
         }
+        mutex_unlock(&pmac_backlight_mutex);
 #endif
         printk("Oops: %s, sig: %ld [#%d]\n", str, err, ++die_counter);
 #ifdef CONFIG_PREEMPT
diff --git a/arch/powerpc/platforms/powermac/backlight.c b/arch/powerpc/platforms/powermac/backlight.c
index 8be2f7d071f0..498b042e1837 100644
--- a/arch/powerpc/platforms/powermac/backlight.c
+++ b/arch/powerpc/platforms/powermac/backlight.c
@@ -3,200 +3,148 @@
  * Contains support for the backlight.
  *
  *   Copyright (C) 2000 Benjamin Herrenschmidt
+ *   Copyright (C) 2006 Michael Hanselmann <linux-kernel@hansmi.ch>
  *
  */
 
 #include <linux/config.h>
 #include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/stddef.h>
-#include <linux/reboot.h>
-#include <linux/nvram.h>
-#include <linux/console.h>
-#include <asm/sections.h>
-#include <asm/ptrace.h>
-#include <asm/io.h>
-#include <asm/pgtable.h>
-#include <asm/system.h>
+#include <linux/fb.h>
+#include <linux/backlight.h>
 #include <asm/prom.h>
-#include <asm/machdep.h>
-#include <asm/nvram.h>
 #include <asm/backlight.h>
 
-#include <linux/adb.h>
-#include <linux/pmu.h>
+#define OLD_BACKLIGHT_MAX 15
 
-static struct backlight_controller *backlighter;
-static void* backlighter_data;
-static int backlight_autosave;
-static int backlight_level = BACKLIGHT_MAX;
-static int backlight_enabled = 1;
-static int backlight_req_level = -1;
-static int backlight_req_enable = -1;
+/* Protect the pmac_backlight variable */
+DEFINE_MUTEX(pmac_backlight_mutex);
 
-static void backlight_callback(void *);
-static DECLARE_WORK(backlight_work, backlight_callback, NULL);
+/* Main backlight storage
+ *
+ * Backlight drivers in this variable are required to have the "props"
+ * attribute set and to have an update_status function.
+ *
+ * We can only store one backlight here, but since Apple laptops have only one
+ * internal display, it doesn't matter. Other backlight drivers can be used
+ * independently.
+ *
+ * Lock ordering:
+ * pmac_backlight_mutex (global, main backlight)
+ *   pmac_backlight->sem (backlight class)
+ */
+struct backlight_device *pmac_backlight;
 
-void register_backlight_controller(struct backlight_controller *ctrler,
-                                          void *data, char *type)
+int pmac_has_backlight_type(const char *type)
 {
-        struct device_node* bk_node;
-        char *prop;
-        int valid = 0;
-
-        /* There's already a matching controller, bail out */
-        if (backlighter != NULL)
-                return;
-
-        bk_node = find_devices("backlight");
-
-#ifdef CONFIG_ADB_PMU
-        /* Special case for the old PowerBook since I can't test on it */
-        backlight_autosave = machine_is_compatible("AAPL,3400/2400")
-                || machine_is_compatible("AAPL,3500");
-        if ((backlight_autosave
-             || machine_is_compatible("AAPL,PowerBook1998")
-             || machine_is_compatible("PowerBook1,1"))
-            && !strcmp(type, "pmu"))
-                valid = 1;
-#endif
+        struct device_node* bk_node = find_devices("backlight");
+
         if (bk_node) {
-                prop = get_property(bk_node, "backlight-control", NULL);
-                if (prop && !strncmp(prop, type, strlen(type)))
-                        valid = 1;
-        }
-        if (!valid)
-                return;
-        backlighter = ctrler;
-        backlighter_data = data;
-
-        if (bk_node && !backlight_autosave)
-                prop = get_property(bk_node, "bklt", NULL);
-        else
-                prop = NULL;
-        if (prop) {
-                backlight_level = ((*prop)+1) >> 1;
-                if (backlight_level > BACKLIGHT_MAX)
-                        backlight_level = BACKLIGHT_MAX;
+                char *prop = get_property(bk_node, "backlight-control", NULL);
+                if (prop && strncmp(prop, type, strlen(type)) == 0)
+                        return 1;
         }
 
-#ifdef CONFIG_ADB_PMU
-        if (backlight_autosave) {
-                struct adb_request req;
-                pmu_request(&req, NULL, 2, 0xd9, 0);
-                while (!req.complete)
-                        pmu_poll();
-                backlight_level = req.reply[0] >> 4;
-        }
-#endif
-        acquire_console_sem();
-        if (!backlighter->set_enable(1, backlight_level, data))
-                backlight_enabled = 1;
-        release_console_sem();
-
-        printk(KERN_INFO "Registered \"%s\" backlight controller,"
-               "level: %d/15\n", type, backlight_level);
+        return 0;
 }
-EXPORT_SYMBOL(register_backlight_controller);
 
-void unregister_backlight_controller(struct backlight_controller
-                                            *ctrler, void *data)
+int pmac_backlight_curve_lookup(struct fb_info *info, int value)
 {
-        /* We keep the current backlight level (for now) */
-        if (ctrler == backlighter && data == backlighter_data)
-                backlighter = NULL;
+        int level = (FB_BACKLIGHT_LEVELS - 1);
+
+        if (info && info->bl_dev) {
+                int i, max = 0;
+
+                /* Look for biggest value */
+                for (i = 0; i < FB_BACKLIGHT_LEVELS; i++)
+                        max = max((int)info->bl_curve[i], max);
+
+                /* Look for nearest value */
+                for (i = 0; i < FB_BACKLIGHT_LEVELS; i++) {
+                        int diff = abs(info->bl_curve[i] - value);
+                        if (diff < max) {
+                                max = diff;
+                                level = i;
+                        }
+                }
+
+        }
+
+        return level;
 }
-EXPORT_SYMBOL(unregister_backlight_controller);
 
-static int __set_backlight_enable(int enable)
+static void pmac_backlight_key(int direction)
 {
-        int rc;
-
-        if (!backlighter)
-                return -ENODEV;
-        acquire_console_sem();
-        rc = backlighter->set_enable(enable, backlight_level,
-                                     backlighter_data);
-        if (!rc)
-                backlight_enabled = enable;
-        release_console_sem();
-        return rc;
+        mutex_lock(&pmac_backlight_mutex);
+        if (pmac_backlight) {
+                struct backlight_properties *props;
+                int brightness;
+
+                down(&pmac_backlight->sem);
+                props = pmac_backlight->props;
+
+                brightness = props->brightness +
+                        ((direction?-1:1) * (props->max_brightness / 15));
+
+                if (brightness < 0)
+                        brightness = 0;
+                else if (brightness > props->max_brightness)
+                        brightness = props->max_brightness;
+
+                props->brightness = brightness;
+                props->update_status(pmac_backlight);
+
+                up(&pmac_backlight->sem);
+        }
+        mutex_unlock(&pmac_backlight_mutex);
 }
-int set_backlight_enable(int enable)
+
+void pmac_backlight_key_up()
 {
-        if (!backlighter)
-                return -ENODEV;
-        backlight_req_enable = enable;
-        schedule_work(&backlight_work);
-        return 0;
+        pmac_backlight_key(0);
 }
 
-EXPORT_SYMBOL(set_backlight_enable);
-
-int get_backlight_enable(void)
+void pmac_backlight_key_down()
 {
-        if (!backlighter)
-                return -ENODEV;
-        return backlight_enabled;
+        pmac_backlight_key(1);
 }
-EXPORT_SYMBOL(get_backlight_enable);
 
-static int __set_backlight_level(int level)
+int pmac_backlight_set_legacy_brightness(int brightness)
 {
-        int rc = 0;
-
-        if (!backlighter)
-                return -ENODEV;
-        if (level < BACKLIGHT_MIN)
-                level = BACKLIGHT_OFF;
-        if (level > BACKLIGHT_MAX)
-                level = BACKLIGHT_MAX;
-        acquire_console_sem();
-        if (backlight_enabled)
-                rc = backlighter->set_level(level, backlighter_data);
-        if (!rc)
-                backlight_level = level;
-        release_console_sem();
-        if (!rc && !backlight_autosave) {
-                level <<=1;
-                if (level & 0x10)
-                        level |= 0x01;
-                // -- todo: save to property "bklt"
+        int error = -ENXIO;
+
+        mutex_lock(&pmac_backlight_mutex);
+        if (pmac_backlight) {
+                struct backlight_properties *props;
+
+                down(&pmac_backlight->sem);
+                props = pmac_backlight->props;
+                props->brightness = brightness *
+                        props->max_brightness / OLD_BACKLIGHT_MAX;
+                props->update_status(pmac_backlight);
+                up(&pmac_backlight->sem);
+
+                error = 0;
         }
-        return rc;
+        mutex_unlock(&pmac_backlight_mutex);
+
+        return error;
 }
-int set_backlight_level(int level)
+
+int pmac_backlight_get_legacy_brightness()
 {
-        if (!backlighter)
-                return -ENODEV;
-        backlight_req_level = level;
-        schedule_work(&backlight_work);
-        return 0;
-}
+        int result = -ENXIO;
 
-EXPORT_SYMBOL(set_backlight_level);
+        mutex_lock(&pmac_backlight_mutex);
+        if (pmac_backlight) {
+                struct backlight_properties *props;
 
-int get_backlight_level(void)
-{
-        if (!backlighter)
-                return -ENODEV;
-        return backlight_level;
-}
-EXPORT_SYMBOL(get_backlight_level);
+                down(&pmac_backlight->sem);
+                props = pmac_backlight->props;
+                result = props->brightness *
+                        OLD_BACKLIGHT_MAX / props->max_brightness;
+                up(&pmac_backlight->sem);
+        }
+        mutex_unlock(&pmac_backlight_mutex);
 
-static void backlight_callback(void *dummy)
-{
-        int level, enable;
-
-        do {
-                level = backlight_req_level;
-                enable = backlight_req_enable;
-                mb();
-
-                if (level >= 0)
-                        __set_backlight_level(level);
-                if (enable >= 0)
-                        __set_backlight_enable(enable);
-        } while(cmpxchg(&backlight_req_level, level, -1) != level ||
-                cmpxchg(&backlight_req_enable, enable, -1) != enable);
+        return result;
 }
diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
index 4735b41c113c..0741df8c41b7 100644
--- a/arch/powerpc/xmon/xmon.c
+++ b/arch/powerpc/xmon/xmon.c
@@ -26,9 +26,6 @@
 #include <asm/prom.h>
 #include <asm/machdep.h>
 #include <asm/xmon.h>
-#ifdef CONFIG_PMAC_BACKLIGHT
-#include <asm/backlight.h>
-#endif
 #include <asm/processor.h>
 #include <asm/pgtable.h>
 #include <asm/mmu.h>