[alsa-devel] [PATCH 4/4] ASoC: davinci-mcasp: Calculate AUXCLK divider when setting up master clocks

[Peter Ujfalusi]

If the McASP is used as clock master and the reference clock is AUXCLK we
can have additional level of divider. The BCLK divider is limited to
maximum 32, if the desired bclk can not be reached with this, the AUXCLK
divider also needs to be used.

Signed-off-by: Peter Ujfalusi <peter.ujfalusi at ti.com>
---
 sound/soc/davinci/davinci-mcasp.c | 29 +++++++++++++++++++++++++----
 1 file changed, 25 insertions(+), 4 deletions(-)

diff --git a/sound/soc/davinci/davinci-mcasp.c b/sound/soc/davinci/davinci-mcasp.c
index 3df9565c1645..0f66fda2c772 100644
--- a/sound/soc/davinci/davinci-mcasp.c
+++ b/sound/soc/davinci/davinci-mcasp.c
@@ -1003,13 +1003,31 @@ static int davinci_mcasp_calc_clk_div(struct davinci_mcasp *mcasp,
 				      unsigned int bclk_freq, bool set)
 {
 	int error_ppm;
-	int div = mcasp->sysclk_freq / bclk_freq;
-	int rem = mcasp->sysclk_freq % bclk_freq;
+	unsigned int sysclk_freq = mcasp->sysclk_freq;
+	u32 reg = mcasp_get_reg(mcasp, DAVINCI_MCASP_AHCLKXCTL_REG);
+	int div = sysclk_freq / bclk_freq;
+	int rem = sysclk_freq % bclk_freq;
+	int aux_div = 1;
+
+	if (div > (ACLKXDIV_MASK + 1)) {
+		if (reg & AHCLKXE) {
+			aux_div = div / (ACLKXDIV_MASK + 1);
+			if (div % (ACLKXDIV_MASK + 1))
+				aux_div++;
+
+			sysclk_freq /= aux_div;
+			div = sysclk_freq / bclk_freq;
+			rem = sysclk_freq % bclk_freq;
+		} else if (set) {
+			dev_warn(mcasp->dev, "Too fast reference clock (%u)\n",
+				 sysclk_freq);
+		}
+	}
 
 	if (rem != 0) {
 		if (div == 0 ||
-		    ((mcasp->sysclk_freq / div) - bclk_freq) >
-		    (bclk_freq - (mcasp->sysclk_freq / (div+1)))) {
+		    ((sysclk_freq / div) - bclk_freq) >
+		    (bclk_freq - (sysclk_freq / (div+1)))) {
 			div++;
 			rem = rem - bclk_freq;
 		}
@@ -1023,6 +1041,9 @@ static int davinci_mcasp_calc_clk_div(struct davinci_mcasp *mcasp,
 				 error_ppm);
 
 		__davinci_mcasp_set_clkdiv(mcasp, MCASP_CLKDIV_BCLK, div, 0);
+		if (reg & AHCLKXE)
+			__davinci_mcasp_set_clkdiv(mcasp, MCASP_CLKDIV_AUXCLK,
+						   aux_div, 0);
 	}
 
 	return error_ppm;
-- 
2.8.2