ASoC: ti: davinci-i2s: Add handling of BP_FC format

McBSP is able to drive bit clock and consume frame clock but BP_FC
format is not handled by McBSP driver.

Add BP_FC format support.
When BP_FC is selected:
- CLKX and CLKR are configured as outputs
- The sample rate generator is configured to be able to provide bit
clock.

Signed-off-by: Bastien Curutchet <[e-mail]>
Acked-by: Peter Ujfalusi <[e-mail]>
Link: https://msgid.link/r/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

sound/soc/ti/davinci-i2s.c

···
 		pcr = DAVINCI_MCBSP_PCR_FSRM | DAVINCI_MCBSP_PCR_FSXM;
 		pcr |= DAVINCI_MCBSP_PCR_SCLKME;
 		break;
+	case SND_SOC_DAIFMT_BP_FC:
+		/* cpu is bitclock provider */
+		pcr = DAVINCI_MCBSP_PCR_CLKXM |
+			DAVINCI_MCBSP_PCR_CLKRM;
+		break;
+
 	case SND_SOC_DAIFMT_BC_FC:
 		if (dev->tdm_slots || dev->slot_width) {
 			dev_err(dev->dev, "TDM is not supported for BC_FC format\n");
···
 		clk_div = dev->clk_div - 1;
 		srgr |= DAVINCI_MCBSP_SRGR_FWID(mcbsp_word_length * 8 - 1);
 		srgr |= DAVINCI_MCBSP_SRGR_FPER(mcbsp_word_length * 16 - 1);
+		clk_div &= 0xFF;
+		srgr |= clk_div;
+		break;
+	case SND_SOC_DAIFMT_BP_FC:
+		if (dev->ext_clk) {
+			freq = clk_get_rate(dev->ext_clk);
+		} else {
+			freq = clk_get_rate(dev->clk);
+			srgr = DAVINCI_MCBSP_SRGR_CLKSM;
+		}
+		if (dev->tdm_slots && dev->slot_width) {
+			clk_div = freq / (params->rate_num * params->rate_den)
+				 / (dev->tdm_slots * dev->slot_width) - 1;
+		} else {
+			clk_div = freq / (mcbsp_word_length * 16) /
+				  params->rate_num * params->rate_den;
+		}
 		clk_div &= 0xFF;
 		srgr |= clk_div;
 		break;