ASoC: rsnd: tidyup ADG

Merge series from Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>:

Renesas Sound has ADG for clock control. Basically it needs
accurately divisible external input clock. But sometimes
sometimes it doesn't have to be accurate for some reason.

We can use ADG clk_i for such case. It came from CPG as
very high rate clock, but is not accurately divisible for
48kHz/44.1kHz rate, but enough for approximate rate.

This patch set support such use case.

sound/soc/sh/rcar/adg.c

@@ -358,8 +358,6 @@ int rsnd_adg_ssi_clk_try_start(struct rsnd_mod *ssi_mod, unsigned int rate)
 		ckr = 0x80000000; /* BRGB output = 48kHz */
 
 	rsnd_mod_bset(adg_mod, BRGCKR, 0x80770000, adg->ckr | ckr);
-	rsnd_mod_write(adg_mod, BRRA,  adg->brga);
-	rsnd_mod_write(adg_mod, BRRB,  adg->brgb);
 
 	dev_dbg(dev, "CLKOUT is based on BRG%c (= %dHz)\n",
 		(ckr) ? 'B' : 'A',
@@ -372,9 +370,16 @@ int rsnd_adg_ssi_clk_try_start(struct rsnd_mod *ssi_mod, unsigned int rate)
 void rsnd_adg_clk_control(struct rsnd_priv *priv, int enable)
 {
 	struct rsnd_adg *adg = rsnd_priv_to_adg(priv);
+	struct rsnd_mod *adg_mod = rsnd_mod_get(adg);
 	struct clk *clk;
 	int i;
 
+	if (enable) {
+		rsnd_mod_bset(adg_mod, BRGCKR, 0x80770000, adg->ckr);
+		rsnd_mod_write(adg_mod, BRRA,  adg->brga);
+		rsnd_mod_write(adg_mod, BRRB,  adg->brgb);
+	}
+
 	for_each_rsnd_clkin(clk, adg, i) {
 		if (enable) {
 			clk_prepare_enable(clk);
@@ -485,12 +490,12 @@ static int rsnd_adg_get_clkout(struct rsnd_priv *priv)
 	struct device_node *np = dev->of_node;
 	struct property *prop;
 	u32 ckr, brgx, brga, brgb;
-	u32 rate, div;
 	u32 req_rate[ADG_HZ_SIZE] = {};
 	uint32_t count = 0;
 	unsigned long req_Hz[ADG_HZ_SIZE];
 	int clkout_size;
 	int i, req_size;
+	int approximate = 0;
 	const char *parent_clk_name = NULL;
 	const char * const *clkout_name;
 	int brg_table[] = {
@@ -501,8 +506,8 @@ static int rsnd_adg_get_clkout(struct rsnd_priv *priv)
 	};
 
 	ckr = 0;
-	brga = 2; /* default 1/6 */
-	brgb = 2; /* default 1/6 */
+	brga = 0xff; /* default */
+	brgb = 0xff; /* default */
 
 	/*
 	 * ADG supports BRRA/BRRB output only
@@ -537,17 +542,41 @@ static int rsnd_adg_get_clkout(struct rsnd_priv *priv)
 	 *	rsnd_adg_ssi_clk_try_start()
 	 *	rsnd_ssi_master_clk_start()
 	 */
+
+	/*
+	 * [APPROXIMATE]
+	 *
+	 * clk_i (internal clock) can't create accurate rate, it will be approximate rate.
+	 *
+	 * <Note>
+	 *
+	 * clk_i needs x2 of required maximum rate.
+	 * see
+	 *	- Minimum division of BRRA/BRRB
+	 *	- rsnd_ssi_clk_query()
+	 *
+	 * Sample Settings for TDM 8ch, 32bit width
+	 *
+	 *	8(ch) x 32(bit) x 44100(Hz) x 2<Note> = 22579200
+	 *	8(ch) x 32(bit) x 48000(Hz) x 2<Note> = 24576000
+	 *
+	 *	clock-frequency = <22579200 24576000>;
+	 */
 	for_each_rsnd_clkin(clk, adg, i) {
+		u32 rate, div;
+
 		rate = clk_get_rate(clk);
 
 		if (0 == rate) /* not used */
 			continue;
 
 		/* BRGA */
-		if (!adg->brg_rate[ADG_HZ_441] && (0 == rate % 44100)) {
-			div = 6;
-			if (req_Hz[ADG_HZ_441])
-				div = rate / req_Hz[ADG_HZ_441];
+
+		if (i == CLKI)
+			/* see [APPROXIMATE] */
+			rate = (clk_get_rate(clk) / req_Hz[ADG_HZ_441]) * req_Hz[ADG_HZ_441];
+		if (!adg->brg_rate[ADG_HZ_441] && req_Hz[ADG_HZ_441] && (0 == rate % 44100)) {
+			div = rate / req_Hz[ADG_HZ_441];
 			brgx = rsnd_adg_calculate_brgx(div);
 			if (BRRx_MASK(brgx) == brgx) {
 				brga = brgx;
@@ -555,14 +584,18 @@ static int rsnd_adg_get_clkout(struct rsnd_priv *priv)
 				ckr |= brg_table[i] << 20;
 				if (req_Hz[ADG_HZ_441])
 					parent_clk_name = __clk_get_name(clk);
+				if (i == CLKI)
+					approximate = 1;
 			}
 		}
 
 		/* BRGB */
-		if (!adg->brg_rate[ADG_HZ_48] && (0 == rate % 48000)) {
-			div = 6;
-			if (req_Hz[ADG_HZ_48])
-				div = rate / req_Hz[ADG_HZ_48];
+
+		if (i == CLKI)
+			/* see [APPROXIMATE] */
+			rate = (clk_get_rate(clk) / req_Hz[ADG_HZ_48]) * req_Hz[ADG_HZ_48];
+		if (!adg->brg_rate[ADG_HZ_48] && req_Hz[ADG_HZ_48] && (0 == rate % 48000)) {
+			div = rate / req_Hz[ADG_HZ_48];
 			brgx = rsnd_adg_calculate_brgx(div);
 			if (BRRx_MASK(brgx) == brgx) {
 				brgb = brgx;
@@ -570,10 +603,19 @@ static int rsnd_adg_get_clkout(struct rsnd_priv *priv)
 				ckr |= brg_table[i] << 16;
 				if (req_Hz[ADG_HZ_48])
 					parent_clk_name = __clk_get_name(clk);
+				if (i == CLKI)
+					approximate = 1;
 			}
 		}
 	}
 
+	if (!(adg->brg_rate[ADG_HZ_48]  && req_Hz[ADG_HZ_48]) &&
+	    !(adg->brg_rate[ADG_HZ_441] && req_Hz[ADG_HZ_441]))
+		goto rsnd_adg_get_clkout_end;
+
+	if (approximate)
+		dev_info(dev, "It uses CLK_I as approximate rate");
+
 	clkout_name = clkout_name_gen2;
 	clkout_size = ARRAY_SIZE(clkout_name_gen2);
 	if (rsnd_is_gen4(priv))