bcm2835-i2s: setup clock only if CPU is clock master

Code ported from bcm2708-i2s driver in Raspberry Pi tree.

RPi commit c14827e ("bcm2708: Allow
option card devices to be configured via DT")

Original work by Zoltan Szenczi, committed to RPi tree by
Phil Elwell.

Signed-off-by: Matthias Reichl <hias@horus.com>

sound/soc/bcm/bcm2835-i2s.c

@@ -411,15 +411,25 @@ static int bcm2835_i2s_hw_params(struct snd_pcm_substream *substream,
 		divf = dividend & BCM2835_CLK_DIVF_MASK;
 	}
 
-	/* Set clock divider */
-	regmap_write(dev->clk_regmap, BCM2835_CLK_PCMDIV_REG, BCM2835_CLK_PASSWD
-			| BCM2835_CLK_DIVI(divi)
-			| BCM2835_CLK_DIVF(divf));
-
-	/* Setup clock, but don't start it yet */
-	regmap_write(dev->clk_regmap, BCM2835_CLK_PCMCTL_REG, BCM2835_CLK_PASSWD
-			| BCM2835_CLK_MASH(mash)
-			| BCM2835_CLK_SRC(clk_src));
+	/* Clock should only be set up here if CPU is clock master */
+	switch (dev->fmt & SND_SOC_DAIFMT_MASTER_MASK) {
+	case SND_SOC_DAIFMT_CBS_CFS:
+	case SND_SOC_DAIFMT_CBS_CFM:
+		/* Set clock divider */
+		regmap_write(dev->clk_regmap, BCM2835_CLK_PCMDIV_REG,
+				  BCM2835_CLK_PASSWD
+				| BCM2835_CLK_DIVI(divi)
+				| BCM2835_CLK_DIVF(divf));
+
+		/* Setup clock, but don't start it yet */
+		regmap_write(dev->clk_regmap, BCM2835_CLK_PCMCTL_REG,
+				  BCM2835_CLK_PASSWD
+				| BCM2835_CLK_MASH(mash)
+				| BCM2835_CLK_SRC(clk_src));
+		break;
+	default:
+		break;
+	}
 
 	/* Setup the frame format */
 	format = BCM2835_I2S_CHEN;