OMAP clockdomains: add usecounting for wakeup and sleep dependencies

Add usecounting for wakeup and sleep dependencies.  In the current
situation, if several functions add dependencies on the same
clockdomains, when the first dependency removal function is called,
the dependency will be incorrectly removed from the hardware.

Add clkdm_clear_all_wkdeps() and clkdm_clear_all_sleepdeps(), which
provide a fast and usecounting-consistent way to clear all hardware
clockdomain dependencies, since accesses to these registers can be
quite slow.  pm{2,3}4xx.c has been updated to use these new functions.
The original version of this patch did not touch these files, which
previously wrote directly to the wkdep registers, and thus confused
the usecounting code.  This problem was found by Kevin Hilman
<khilman@deeprootsystems.com>.

N.B.: This patch introduces one significant functional difference over
the previous pm34xx.c code: sleepdeps are now cleared during
clockdomain initialization, whereas previously they were left
untouched.  This has been tested by Kevin and confirmed to work.

The original version of this patch also did not take into
consideration that some clockdomains do not have sleep or wakeup
dependency sources, which caused NULL pointer dereferences.  This
problem was debugged and fixed by Kevin Hilman
<khilman@deeprootsystems.com>.

Signed-off-by: Paul Walmsley <paul@pwsan.com>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Cc: Jouni Högander <jouni.hogander@nokia.com>

1 files changed, 30 insertions, 19 deletions

diff --git a/arch/arm/mach-omap2/pm24xx.c b/arch/arm/mach-omap2/pm24xx.c
index 754381857cb6..374299ea7ade 100644
--- a/arch/arm/mach-omap2/pm24xx.c
+++ b/arch/arm/mach-omap2/pm24xx.c
@@ -57,11 +57,8 @@ static void (*omap2_sram_idle)(void);
 static void (*omap2_sram_suspend)(u32 dllctrl, void __iomem *sdrc_dlla_ctrl,
                                   void __iomem *sdrc_power);
 
-static struct powerdomain *mpu_pwrdm;
-static struct powerdomain *core_pwrdm;
-
-static struct clockdomain *dsp_clkdm;
-static struct clockdomain *gfx_clkdm;
+static struct powerdomain *mpu_pwrdm, *core_pwrdm;
+static struct clockdomain *dsp_clkdm, *mpu_clkdm, *wkup_clkdm, *gfx_clkdm;
 
 static struct clk *osc_ck, *emul_ck;
 
@@ -334,9 +331,17 @@ static struct platform_suspend_ops omap_pm_ops = {
         .valid          = suspend_valid_only_mem,
 };
 
-static int _pm_clkdm_enable_hwsup(struct clockdomain *clkdm, void *unused)
+/* XXX This function should be shareable between OMAP2xxx and OMAP3 */
+static int __init clkdms_setup(struct clockdomain *clkdm, void *unused)
 {
-        omap2_clkdm_allow_idle(clkdm);
+        clkdm_clear_all_wkdeps(clkdm);
+        clkdm_clear_all_sleepdeps(clkdm);
+
+        if (clkdm->flags & CLKDM_CAN_ENABLE_AUTO)
+                omap2_clkdm_allow_idle(clkdm);
+        else if (clkdm->flags & CLKDM_CAN_FORCE_SLEEP &&
+                 atomic_read(&clkdm->usecount) == 0)
+                omap2_clkdm_sleep(clkdm);
         return 0;
 }
 
@@ -349,14 +354,6 @@ static void __init prcm_setup_regs(void)
         prm_write_mod_reg(OMAP24XX_AUTOIDLE, OCP_MOD,
                           OMAP2_PRCM_SYSCONFIG_OFFSET);
 
-        /* Set all domain wakeup dependencies */
-        prm_write_mod_reg(OMAP_EN_WKUP_MASK, MPU_MOD, PM_WKDEP);
-        prm_write_mod_reg(0, OMAP24XX_DSP_MOD, PM_WKDEP);
-        prm_write_mod_reg(0, GFX_MOD, PM_WKDEP);
-        prm_write_mod_reg(0, CORE_MOD, PM_WKDEP);
-        if (cpu_is_omap2430())
-                prm_write_mod_reg(0, OMAP2430_MDM_MOD, PM_WKDEP);
-
         /*
          * Set CORE powerdomain memory banks to retain their contents
          * during RETENTION
@@ -385,8 +382,12 @@ static void __init prcm_setup_regs(void)
         pwrdm_set_next_pwrst(pwrdm, PWRDM_POWER_OFF);
         omap2_clkdm_sleep(gfx_clkdm);
 
-        /* Enable clockdomain hardware-supervised control for all clkdms */
-        clkdm_for_each(_pm_clkdm_enable_hwsup, NULL);
+        /*
+         * Clear clockdomain wakeup dependencies and enable
+         * hardware-supervised idle for all clkdms
+         */
+        clkdm_for_each(clkdms_setup, NULL);
+        clkdm_add_wkdep(mpu_clkdm, wkup_clkdm);
 
         /* Enable clock autoidle for all domains */
         cm_write_mod_reg(OMAP24XX_AUTO_CAM |
@@ -482,7 +483,7 @@ static int __init omap2_pm_init(void)
         l = prm_read_mod_reg(OCP_MOD, OMAP2_PRCM_REVISION_OFFSET);
         printk(KERN_INFO "PRCM revision %d.%d\n", (l >> 4) & 0x0f, l & 0x0f);
 
-        /* Look up important powerdomains, clockdomains */
+        /* Look up important powerdomains */
 
         mpu_pwrdm = pwrdm_lookup("mpu_pwrdm");
         if (!mpu_pwrdm)
@@ -492,9 +493,19 @@ static int __init omap2_pm_init(void)
         if (!core_pwrdm)
                 pr_err("PM: core_pwrdm not found\n");
 
+        /* Look up important clockdomains */
+
+        mpu_clkdm = clkdm_lookup("mpu_clkdm");
+        if (!mpu_clkdm)
+                pr_err("PM: mpu_clkdm not found\n");
+
+        wkup_clkdm = clkdm_lookup("wkup_clkdm");
+        if (!wkup_clkdm)
+                pr_err("PM: wkup_clkdm not found\n");
+
         dsp_clkdm = clkdm_lookup("dsp_clkdm");
         if (!dsp_clkdm)
-                pr_err("PM: mpu_clkdm not found\n");
+                pr_err("PM: dsp_clkdm not found\n");
 
         gfx_clkdm = clkdm_lookup("gfx_clkdm");
         if (!gfx_clkdm)