ASoC: rsnd: add SRC (Sampling Rate Converter) support

This patch adds SRC support to Renesas sound driver.
SRC converts sampling rate between codec <-> cpu.
It needs special codec chip,
or very simple DA/AD converter to use it.
This patch was tested via ak4554 codec,
and supports Gen1 only at this point.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@linaro.org>

1 files changed, 145 insertions, 7 deletions

diff --git a/sound/soc/sh/rcar/scu.c b/sound/soc/sh/rcar/scu.c
index 5f4f57206faf..1406dd8d9ed2 100644
--- a/sound/soc/sh/rcar/scu.c
+++ b/sound/soc/sh/rcar/scu.c
@@ -13,9 +13,13 @@
 struct rsnd_scu {
         struct rsnd_scu_platform_info *info; /* rcar_snd.h */
         struct rsnd_mod mod;
+        struct clk *clk;
 };
 
 #define rsnd_scu_mode_flags(p) ((p)->info->flags)
+#define rsnd_scu_convert_rate(p) ((p)->info->convert_rate)
+
+#define RSND_SCU_NAME_SIZE 16
 
 /*
  * ADINR
@@ -26,6 +30,15 @@ struct rsnd_scu {
 #define OTBL_18         (6 << 16)
 #define OTBL_16         (8 << 16)
 
+/*
+ *              image of SRC (Sampling Rate Converter)
+ *
+ * 96kHz   <-> +-----+  48kHz   +-----+  48kHz  +-------+
+ * 48kHz   <-> | SRC | <------> | SSI | <-----> | codec |
+ * 44.1kHz <-> +-----+          +-----+         +-------+
+ * ...
+ *
+ */
 
 #define rsnd_mod_to_scu(_mod)   \
         container_of((_mod), struct rsnd_scu, mod)
@@ -56,7 +69,7 @@ static int rsnd_src_set_route_if_gen1(struct rsnd_priv *priv,
                 { 0x3, 28, }, /* 7 */
                 { 0x3, 30, }, /* 8 */
         };
-
+        struct rsnd_scu *scu = rsnd_mod_to_scu(mod);
         u32 mask;
         u32 val;
         int shift;
@@ -86,9 +99,18 @@ static int rsnd_src_set_route_if_gen1(struct rsnd_priv *priv,
          */
         shift   = (id % 4) * 8;
         mask    = 0x1F << shift;
-        if (8 == id) /* SRU8 is very special */
+
+        /*
+         * ADG is used as source clock if SRC was used,
+         * then, SSI WS is used as destination clock.
+         * SSI WS is used as source clock if SRC is not used
+         * (when playback, source/destination become reverse when capture)
+         */
+        if (rsnd_scu_convert_rate(scu)) /* use ADG */
+                val = 0;
+        else if (8 == id)               /* use SSI WS, but SRU8 is special */
                 val = id << shift;
-        else
+        else                            /* use SSI WS */
                 val = (id + 1) << shift;
 
         switch (id / 4) {
@@ -106,14 +128,45 @@ static int rsnd_src_set_route_if_gen1(struct rsnd_priv *priv,
         return 0;
 }
 
-static int rsnd_scu_rate_ctrl(struct rsnd_priv *priv,
+unsigned int rsnd_scu_get_ssi_rate(struct rsnd_priv *priv,
+                                   struct rsnd_mod *ssi_mod,
+                                   struct snd_pcm_runtime *runtime)
+{
+        struct rsnd_scu *scu;
+        unsigned int rate;
+
+        /* this function is assuming SSI id = SCU id here */
+        scu = rsnd_mod_to_scu(rsnd_scu_mod_get(priv, rsnd_mod_id(ssi_mod)));
+
+        /*
+         * return convert rate if SRC is used,
+         * otherwise, return runtime->rate as usual
+         */
+        rate = rsnd_scu_convert_rate(scu);
+        if (!rate)
+                rate = runtime->rate;
+
+        return rate;
+}
+
+static int rsnd_scu_convert_rate_ctrl(struct rsnd_priv *priv,
                               struct rsnd_mod *mod,
                               struct rsnd_dai *rdai,
                               struct rsnd_dai_stream *io)
 {
         struct snd_pcm_runtime *runtime = rsnd_io_to_runtime(io);
+        struct rsnd_scu *scu = rsnd_mod_to_scu(mod);
+        u32 convert_rate = rsnd_scu_convert_rate(scu);
         u32 adinr = runtime->channels;
 
+        /* set/clear soft reset */
+        rsnd_mod_write(mod, SRC_SWRSR, 0);
+        rsnd_mod_write(mod, SRC_SWRSR, 1);
+
+        /* Initialize the operation of the SRC internal circuits */
+        rsnd_mod_write(mod, SRC_SRCIR, 1);
+
+        /* Set channel number and output bit length */
         switch (runtime->sample_bits) {
         case 16:
                 adinr |= OTBL_16;
@@ -124,9 +177,42 @@ static int rsnd_scu_rate_ctrl(struct rsnd_priv *priv,
         default:
                 return -EIO;
         }
-
         rsnd_mod_write(mod, SRC_ADINR, adinr);
 
+        if (convert_rate) {
+                u32 fsrate = 0x0400000 / convert_rate * runtime->rate;
+                int ret;
+
+                /* Enable the initial value of IFS */
+                rsnd_mod_write(mod, SRC_IFSCR, 1);
+
+                /* Set initial value of IFS */
+                rsnd_mod_write(mod, SRC_IFSVR, fsrate);
+
+                /* Select SRC mode (fixed value) */
+                rsnd_mod_write(mod, SRC_SRCCR, 0x00010110);
+
+                /* Set the restriction value of the FS ratio (98%) */
+                rsnd_mod_write(mod, SRC_MNFSR, fsrate / 100 * 98);
+
+                if (rsnd_is_gen1(priv)) {
+                        /* no SRC_BFSSR settings, since SRC_SRCCR::BUFMD is 0 */
+                }
+
+                /* set convert clock */
+                ret = rsnd_adg_set_convert_clk(priv, mod,
+                                               runtime->rate,
+                                               convert_rate);
+                if (ret < 0)
+                        return ret;
+        }
+
+        /* Cancel the initialization and operate the SRC function */
+        rsnd_mod_write(mod, SRC_SRCIR, 0);
+
+        /* use DMA transfer */
+        rsnd_mod_write(mod, BUSIF_MODE, 1);
+
         return 0;
 }
 
@@ -135,6 +221,7 @@ static int rsnd_scu_transfer_start(struct rsnd_priv *priv,
                                    struct rsnd_dai *rdai,
                                    struct rsnd_dai_stream *io)
 {
+        struct rsnd_scu *scu = rsnd_mod_to_scu(mod);
         int id = rsnd_mod_id(mod);
         u32 val;
 
@@ -143,7 +230,28 @@ static int rsnd_scu_transfer_start(struct rsnd_priv *priv,
                 rsnd_mod_bset(mod, SRC_ROUTE_CTRL, val, val);
         }
 
-        rsnd_mod_write(mod, BUSIF_MODE, 1);
+        if (rsnd_scu_convert_rate(scu))
+                rsnd_mod_write(mod, SRC_ROUTE_MODE0, 1);
+
+        return 0;
+}
+
+static int rsnd_scu_transfer_stop(struct rsnd_priv *priv,
+                                  struct rsnd_mod *mod,
+                                  struct rsnd_dai *rdai,
+                                  struct rsnd_dai_stream *io)
+{
+        struct rsnd_scu *scu = rsnd_mod_to_scu(mod);
+        int id = rsnd_mod_id(mod);
+        u32 mask;
+
+        if (rsnd_is_gen1(priv)) {
+                mask = (1 << id);
+                rsnd_mod_bset(mod, SRC_ROUTE_CTRL, mask, 0);
+        }
+
+        if (rsnd_scu_convert_rate(scu))
+                rsnd_mod_write(mod, SRC_ROUTE_MODE0, 0);
 
         return 0;
 }
@@ -161,6 +269,7 @@ static int rsnd_scu_start(struct rsnd_mod *mod,
                           struct rsnd_dai_stream *io)
 {
         struct rsnd_priv *priv = rsnd_mod_to_priv(mod);
+        struct rsnd_scu *scu = rsnd_mod_to_scu(mod);
         struct device *dev = rsnd_priv_to_dev(priv);
         int ret;
 
@@ -175,13 +284,15 @@ static int rsnd_scu_start(struct rsnd_mod *mod,
                 return 0;
         }
 
+        clk_enable(scu->clk);
+
         /* it use DMA transter */
 
         ret = rsnd_src_set_route_if_gen1(priv, mod, rdai, io);
         if (ret < 0)
                 return ret;
 
-        ret = rsnd_scu_rate_ctrl(priv, mod, rdai, io);
+        ret = rsnd_scu_convert_rate_ctrl(priv, mod, rdai, io);
         if (ret < 0)
                 return ret;
 
@@ -194,9 +305,27 @@ static int rsnd_scu_start(struct rsnd_mod *mod,
         return 0;
 }
 
+static int rsnd_scu_stop(struct rsnd_mod *mod,
+                          struct rsnd_dai *rdai,
+                          struct rsnd_dai_stream *io)
+{
+        struct rsnd_priv *priv = rsnd_mod_to_priv(mod);
+        struct rsnd_scu *scu = rsnd_mod_to_scu(mod);
+
+        if (!rsnd_scu_hpbif_is_enable(mod))
+                return 0;
+
+        rsnd_scu_transfer_stop(priv, mod, rdai, io);
+
+        clk_disable(scu->clk);
+
+        return 0;
+}
+
 static struct rsnd_mod_ops rsnd_scu_ops = {
         .name   = "scu",
         .start  = rsnd_scu_start,
+        .stop   = rsnd_scu_stop,
 };
 
 struct rsnd_mod *rsnd_scu_mod_get(struct rsnd_priv *priv, int id)
@@ -212,6 +341,8 @@ int rsnd_scu_probe(struct platform_device *pdev,
 {
         struct device *dev = rsnd_priv_to_dev(priv);
         struct rsnd_scu *scu;
+        struct clk *clk;
+        char name[RSND_SCU_NAME_SIZE];
         int i, nr;
 
         /*
@@ -228,9 +359,16 @@ int rsnd_scu_probe(struct platform_device *pdev,
         priv->scu       = scu;
 
         for_each_rsnd_scu(scu, priv, i) {
+                snprintf(name, RSND_SCU_NAME_SIZE, "scu.%d", i);
+
+                clk = devm_clk_get(dev, name);
+                if (IS_ERR(clk))
+                        return PTR_ERR(clk);
+
                 rsnd_mod_init(priv, &scu->mod,
                               &rsnd_scu_ops, i);
                 scu->info = &info->scu_info[i];
+                scu->clk = clk;
 
                 dev_dbg(dev, "SCU%d probed\n", i);
         }