[PATCH 2/2] [RFC] cpufreq: omap: scale regulator from clk notifier

On Saturday 14 July 2012 05:46 AM, Mike Turquette wrote:

This patch moves direct control of the MPU voltage regulator out of the
cpufreq driver .target callback and instead puts that logic into a clock
rate change notifier callback.

The same frequency/voltage lookup via the OPP library is present, except
that the calls to regulator_set_voltage are done from the clock
framework instead of cpufreq.

Ideally it would be nice to reduce the .target callback for OMAP's
cpufreq driver to a simple call to clk_set_rate.  For now there is still
some other stuff needed there (jiffies per loop, rounding the rate, etc
etc).

Not-signed-off-by: Mike Turquette[off-list ref]
---
  drivers/cpufreq/omap-cpufreq.c |  154 +++++++++++++++++++++++++---------------
  1 file changed, 96 insertions(+), 58 deletions(-)

<snip>

-static int __init omap_cpufreq_init(void)
+static int mpu_clk_volt_scale_handler(struct notifier_block *nb,
+	unsigned long flags, void *data)
  {
-	if (cpu_is_omap24xx())
-		mpu_clk_name = "virt_prcm_set";
-	else if (cpu_is_omap34xx())
-		mpu_clk_name = "dpll1_ck";
-	else if (cpu_is_omap44xx())
-		mpu_clk_name = "dpll_mpu_ck";
+	struct clk_notifier_data *cnd = data;
+	unsigned long tol;
+	int ret, volt_new, volt_old;
+	struct opp *opp;

-	if (!mpu_clk_name) {
-		pr_err("%s: unsupported Silicon?\n", __func__);
-		return -EINVAL;
+	volt_old = regulator_get_voltage(mpu_reg);
+	opp = opp_find_freq_exact(mpu_dev, cnd->new_rate, true);
+	volt_new = opp_get_voltage(opp);
+
+	tol = volt_new * OPP_TOLERANCE / 100;
+
+	/* scaling up?  scale voltage before frequency */
+	if (cnd->new_rate>  cnd->old_rate) {
+		dev_dbg(mpu_dev, "cpufreq-omap: %d mV -->  %d mV\n",
+				volt_old, volt_new);
+
+		ret = regulator_set_voltage(mpu_reg, volt_new - tol, volt_new + tol);
+
+		if (ret<  0) {
+			dev_warn(mpu_dev, "%s: unable to scale voltage up.\n",
+				 __func__);
+			return NOTIFY_BAD;
+		}
+	}
+
+	/* scaling down?  scale voltage after frequency */
+	if (cnd->new_rate<  cnd->old_rate) {
+		dev_dbg(mpu_dev, "cpufreq-omap: %d mV -->  %d mV\n",
+				volt_old, volt_new);
+
+		ret = regulator_set_voltage(mpu_reg, volt_new - tol, volt_new + tol);
+
+		if (ret<  0) {
+			dev_warn(mpu_dev, "%s: unable to scale voltage down.\n",
+				 __func__);
+			return NOTIFY_BAD;
+		}
  	}

How are you checking pre and post rate change condition here? Need 
switch case for event?

+	return NOTIFY_OK;
+}
+
+static struct notifier_block mpu_clk_volt_scale_nb = {
+	.notifier_call = mpu_clk_volt_scale_handler,
+};
+
+