mfd: twl6040: Handle mclk used for HPPLL and optional internal clock source

On some boards, like omap5-uevm the MCLK is gated by default and in order
to be able to use the High performance modes of twl6040 it need to be
enabled by SW.
Add support for handling the MCLK source clock via CCF.
At the same time lower the print priority of the notification that the 32K
clock is not provided and it is not going to be handled by the driver.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

drivers/mfd/twl6040.c

@@ -323,8 +323,7 @@ int twl6040_power(struct twl6040 *twl6040, int on)
 
 		/* Default PLL configuration after power up */
 		twl6040->pll = TWL6040_SYSCLK_SEL_LPPLL;
-		twl6040->sysclk = 19200000;
-		twl6040->mclk = 32768;
+		twl6040->sysclk_rate = 19200000;
 	} else {
 		/* already powered-down */
 		if (!twl6040->power_count) {
@@ -352,8 +351,12 @@ int twl6040_power(struct twl6040 *twl6040, int on)
 		regcache_cache_only(twl6040->regmap, true);
 		regcache_mark_dirty(twl6040->regmap);
 
-		twl6040->sysclk = 0;
-		twl6040->mclk = 0;
+		twl6040->sysclk_rate = 0;
+
+		if (twl6040->pll == TWL6040_SYSCLK_SEL_HPPLL) {
+			clk_disable_unprepare(twl6040->mclk);
+			twl6040->mclk_rate = 0;
+		}
 
 		clk_disable_unprepare(twl6040->clk32k);
 	}
@@ -377,15 +380,15 @@ int twl6040_set_pll(struct twl6040 *twl6040, int pll_id,
 
 	/* Force full reconfiguration when switching between PLL */
 	if (pll_id != twl6040->pll) {
-		twl6040->sysclk = 0;
-		twl6040->mclk = 0;
+		twl6040->sysclk_rate = 0;
+		twl6040->mclk_rate = 0;
 	}
 
 	switch (pll_id) {
 	case TWL6040_SYSCLK_SEL_LPPLL:
 		/* low-power PLL divider */
 		/* Change the sysclk configuration only if it has been canged */
-		if (twl6040->sysclk != freq_out) {
+		if (twl6040->sysclk_rate != freq_out) {
 			switch (freq_out) {
 			case 17640000:
 				lppllctl |= TWL6040_LPLLFIN;
@@ -427,6 +430,8 @@ int twl6040_set_pll(struct twl6040 *twl6040, int pll_id,
 			ret = -EINVAL;
 			goto pll_out;
 		}
+
+		clk_disable_unprepare(twl6040->mclk);
 		break;
 	case TWL6040_SYSCLK_SEL_HPPLL:
 		/* high-performance PLL can provide only 19.2 MHz */
@@ -437,7 +442,7 @@ int twl6040_set_pll(struct twl6040 *twl6040, int pll_id,
 			goto pll_out;
 		}
 
-		if (twl6040->mclk != freq_in) {
+		if (twl6040->mclk_rate != freq_in) {
 			hppllctl &= ~TWL6040_MCLK_MSK;
 
 			switch (freq_in) {
@@ -468,6 +473,9 @@ int twl6040_set_pll(struct twl6040 *twl6040, int pll_id,
 				goto pll_out;
 			}
 
+			/* When switching to HPPLL, enable the mclk first */
+			if (pll_id != twl6040->pll)
+				clk_prepare_enable(twl6040->mclk);
 			/*
 			 * enable clock slicer to ensure input waveform is
 			 * square
@@ -483,6 +491,8 @@ int twl6040_set_pll(struct twl6040 *twl6040, int pll_id,
 			lppllctl &= ~TWL6040_LPLLENA;
 			twl6040_reg_write(twl6040, TWL6040_REG_LPPLLCTL,
 					  lppllctl);
+
+			twl6040->mclk_rate = freq_in;
 		}
 		break;
 	default:
@@ -491,8 +501,7 @@ int twl6040_set_pll(struct twl6040 *twl6040, int pll_id,
 		goto pll_out;
 	}
 
-	twl6040->sysclk = freq_out;
-	twl6040->mclk = freq_in;
+	twl6040->sysclk_rate = freq_out;
 	twl6040->pll = pll_id;
 
 pll_out:
@@ -512,7 +521,7 @@ EXPORT_SYMBOL(twl6040_get_pll);
 
 unsigned int twl6040_get_sysclk(struct twl6040 *twl6040)
 {
-	return twl6040->sysclk;
+	return twl6040->sysclk_rate;
 }
 EXPORT_SYMBOL(twl6040_get_sysclk);
 
@@ -655,10 +664,18 @@ static int twl6040_probe(struct i2c_client *client,
 	if (IS_ERR(twl6040->clk32k)) {
 		if (PTR_ERR(twl6040->clk32k) == -EPROBE_DEFER)
 			return -EPROBE_DEFER;
-		dev_info(&client->dev, "clk32k is not handled\n");
+		dev_dbg(&client->dev, "clk32k is not handled\n");
 		twl6040->clk32k = NULL;
 	}
 
+	twl6040->mclk = devm_clk_get(&client->dev, "mclk");
+	if (IS_ERR(twl6040->mclk)) {
+		if (PTR_ERR(twl6040->mclk) == -EPROBE_DEFER)
+			return -EPROBE_DEFER;
+		dev_dbg(&client->dev, "mclk is not handled\n");
+		twl6040->mclk = NULL;
+	}
+
 	twl6040->supplies[0].supply = "vio";
 	twl6040->supplies[1].supply = "v2v1";
 	ret = devm_regulator_bulk_get(&client->dev, TWL6040_NUM_SUPPLIES,