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Subject[RESEND PATCH 2/2] ASoC: stm32: i2s: add master clock provider
Date
From: Olivier Moysan <olivier.moysan@st.com>

Add master clock generation support in STM32 I2S driver.
The master clock provided by I2S can be used to feed a codec.

Signed-off-by: Olivier Moysan <olivier.moysan@foss.st.com>
---
sound/soc/stm/stm32_i2s.c | 310 ++++++++++++++++++++++++++++++++------
1 file changed, 266 insertions(+), 44 deletions(-)

diff --git a/sound/soc/stm/stm32_i2s.c b/sound/soc/stm/stm32_i2s.c
index 7c4d63c33f15..7d1672cf78cc 100644
--- a/sound/soc/stm/stm32_i2s.c
+++ b/sound/soc/stm/stm32_i2s.c
@@ -8,6 +8,7 @@

#include <linux/bitfield.h>
#include <linux/clk.h>
+#include <linux/clk-provider.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/of_irq.h>
@@ -196,6 +197,9 @@ enum i2s_datlen {
#define STM32_I2S_IS_MASTER(x) ((x)->ms_flg == I2S_MS_MASTER)
#define STM32_I2S_IS_SLAVE(x) ((x)->ms_flg == I2S_MS_SLAVE)

+#define STM32_I2S_NAME_LEN 32
+#define STM32_I2S_RATE_11K 11025
+
/**
* struct stm32_i2s_data - private data of I2S
* @regmap_conf: I2S register map configuration pointer
@@ -206,6 +210,7 @@ enum i2s_datlen {
* @dma_data_rx: dma configuration data for tx channel
* @substream: PCM substream data pointer
* @i2sclk: kernel clock feeding the I2S clock generator
+ * @i2smclk: master clock from I2S mclk provider
* @pclk: peripheral clock driving bus interface
* @x8kclk: I2S parent clock for sampling frequencies multiple of 8kHz
* @x11kclk: I2S parent clock for sampling frequencies multiple of 11kHz
@@ -215,6 +220,9 @@ enum i2s_datlen {
* @irq_lock: prevent race condition with IRQ
* @mclk_rate: master clock frequency (Hz)
* @fmt: DAI protocol
+ * @divider: prescaler division ratio
+ * @div: prescaler div field
+ * @odd: prescaler odd field
* @refcount: keep count of opened streams on I2S
* @ms_flg: master mode flag.
*/
@@ -227,6 +235,7 @@ struct stm32_i2s_data {
struct snd_dmaengine_dai_dma_data dma_data_rx;
struct snd_pcm_substream *substream;
struct clk *i2sclk;
+ struct clk *i2smclk;
struct clk *pclk;
struct clk *x8kclk;
struct clk *x11kclk;
@@ -236,10 +245,210 @@ struct stm32_i2s_data {
spinlock_t irq_lock; /* used to prevent race condition with IRQ */
unsigned int mclk_rate;
unsigned int fmt;
+ unsigned int divider;
+ unsigned int div;
+ bool odd;
int refcount;
int ms_flg;
};

+struct stm32_i2smclk_data {
+ struct clk_hw hw;
+ unsigned long freq;
+ struct stm32_i2s_data *i2s_data;
+};
+
+#define to_mclk_data(_hw) container_of(_hw, struct stm32_i2smclk_data, hw)
+
+static int stm32_i2s_calc_clk_div(struct stm32_i2s_data *i2s,
+ unsigned long input_rate,
+ unsigned long output_rate)
+{
+ unsigned int ratio, div, divider = 1;
+ bool odd;
+
+ ratio = DIV_ROUND_CLOSEST(input_rate, output_rate);
+
+ /* Check the parity of the divider */
+ odd = ratio & 0x1;
+
+ /* Compute the div prescaler */
+ div = ratio >> 1;
+
+ /* If div is 0 actual divider is 1 */
+ if (div) {
+ divider = ((2 * div) + odd);
+ dev_dbg(&i2s->pdev->dev, "Divider: 2*%d(div)+%d(odd) = %d\n",
+ div, odd, divider);
+ }
+
+ /* Division by three is not allowed by I2S prescaler */
+ if ((div == 1 && odd) || div > I2S_CGFR_I2SDIV_MAX) {
+ dev_err(&i2s->pdev->dev, "Wrong divider setting\n");
+ return -EINVAL;
+ }
+
+ if (input_rate % divider)
+ dev_dbg(&i2s->pdev->dev,
+ "Rate not accurate. requested (%ld), actual (%ld)\n",
+ output_rate, input_rate / divider);
+
+ i2s->div = div;
+ i2s->odd = odd;
+ i2s->divider = divider;
+
+ return 0;
+}
+
+static int stm32_i2s_set_clk_div(struct stm32_i2s_data *i2s)
+{
+ u32 cgfr, cgfr_mask;
+
+ cgfr = I2S_CGFR_I2SDIV_SET(i2s->div) | (i2s->odd << I2S_CGFR_ODD_SHIFT);
+ cgfr_mask = I2S_CGFR_I2SDIV_MASK | I2S_CGFR_ODD;
+
+ return regmap_update_bits(i2s->regmap, STM32_I2S_CGFR_REG,
+ cgfr_mask, cgfr);
+}
+
+static int stm32_i2s_set_parent_clock(struct stm32_i2s_data *i2s,
+ unsigned int rate)
+{
+ struct platform_device *pdev = i2s->pdev;
+ struct clk *parent_clk;
+ int ret;
+
+ if (!(rate % STM32_I2S_RATE_11K))
+ parent_clk = i2s->x11kclk;
+ else
+ parent_clk = i2s->x8kclk;
+
+ ret = clk_set_parent(i2s->i2sclk, parent_clk);
+ if (ret)
+ dev_err(&pdev->dev,
+ "Error %d setting i2sclk parent clock\n", ret);
+
+ return ret;
+}
+
+static long stm32_i2smclk_round_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long *prate)
+{
+ struct stm32_i2smclk_data *mclk = to_mclk_data(hw);
+ struct stm32_i2s_data *i2s = mclk->i2s_data;
+ int ret;
+
+ ret = stm32_i2s_calc_clk_div(i2s, *prate, rate);
+ if (ret)
+ return ret;
+
+ mclk->freq = *prate / i2s->divider;
+
+ return mclk->freq;
+}
+
+static unsigned long stm32_i2smclk_recalc_rate(struct clk_hw *hw,
+ unsigned long parent_rate)
+{
+ struct stm32_i2smclk_data *mclk = to_mclk_data(hw);
+
+ return mclk->freq;
+}
+
+static int stm32_i2smclk_set_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long parent_rate)
+{
+ struct stm32_i2smclk_data *mclk = to_mclk_data(hw);
+ struct stm32_i2s_data *i2s = mclk->i2s_data;
+ int ret;
+
+ ret = stm32_i2s_calc_clk_div(i2s, parent_rate, rate);
+ if (ret)
+ return ret;
+
+ ret = stm32_i2s_set_clk_div(i2s);
+ if (ret)
+ return ret;
+
+ mclk->freq = rate;
+
+ return 0;
+}
+
+static int stm32_i2smclk_enable(struct clk_hw *hw)
+{
+ struct stm32_i2smclk_data *mclk = to_mclk_data(hw);
+ struct stm32_i2s_data *i2s = mclk->i2s_data;
+
+ dev_dbg(&i2s->pdev->dev, "Enable master clock\n");
+
+ return regmap_update_bits(i2s->regmap, STM32_I2S_CGFR_REG,
+ I2S_CGFR_MCKOE, I2S_CGFR_MCKOE);
+}
+
+static void stm32_i2smclk_disable(struct clk_hw *hw)
+{
+ struct stm32_i2smclk_data *mclk = to_mclk_data(hw);
+ struct stm32_i2s_data *i2s = mclk->i2s_data;
+
+ dev_dbg(&i2s->pdev->dev, "Disable master clock\n");
+
+ regmap_update_bits(i2s->regmap, STM32_I2S_CGFR_REG, I2S_CGFR_MCKOE, 0);
+}
+
+static const struct clk_ops mclk_ops = {
+ .enable = stm32_i2smclk_enable,
+ .disable = stm32_i2smclk_disable,
+ .recalc_rate = stm32_i2smclk_recalc_rate,
+ .round_rate = stm32_i2smclk_round_rate,
+ .set_rate = stm32_i2smclk_set_rate,
+};
+
+static int stm32_i2s_add_mclk_provider(struct stm32_i2s_data *i2s)
+{
+ struct clk_hw *hw;
+ struct stm32_i2smclk_data *mclk;
+ struct device *dev = &i2s->pdev->dev;
+ const char *pname = __clk_get_name(i2s->i2sclk);
+ char *mclk_name, *p, *s = (char *)pname;
+ int ret, i = 0;
+
+ mclk = devm_kzalloc(dev, sizeof(*mclk), GFP_KERNEL);
+ if (!mclk)
+ return -ENOMEM;
+
+ mclk_name = devm_kcalloc(dev, sizeof(char),
+ STM32_I2S_NAME_LEN, GFP_KERNEL);
+ if (!mclk_name)
+ return -ENOMEM;
+
+ /*
+ * Forge mclk clock name from parent clock name and suffix.
+ * String after "_" char is stripped in parent name.
+ */
+ p = mclk_name;
+ while (*s && *s != '_' && (i < (STM32_I2S_NAME_LEN - 7))) {
+ *p++ = *s++;
+ i++;
+ }
+ strcat(p, "_mclk");
+
+ mclk->hw.init = CLK_HW_INIT(mclk_name, pname, &mclk_ops, 0);
+ mclk->i2s_data = i2s;
+ hw = &mclk->hw;
+
+ dev_dbg(dev, "Register master clock %s\n", mclk_name);
+ ret = devm_clk_hw_register(&i2s->pdev->dev, hw);
+ if (ret) {
+ dev_err(dev, "mclk register fails with error %d\n", ret);
+ return ret;
+ }
+ i2s->i2smclk = hw->clk;
+
+ /* register mclk provider */
+ return devm_of_clk_add_hw_provider(dev, of_clk_hw_simple_get, hw);
+}
+
static irqreturn_t stm32_i2s_isr(int irq, void *devid)
{
struct stm32_i2s_data *i2s = (struct stm32_i2s_data *)devid;
@@ -405,18 +614,46 @@ static int stm32_i2s_set_sysclk(struct snd_soc_dai *cpu_dai,
int clk_id, unsigned int freq, int dir)
{
struct stm32_i2s_data *i2s = snd_soc_dai_get_drvdata(cpu_dai);
+ int ret = 0;

- dev_dbg(cpu_dai->dev, "I2S MCLK frequency is %uHz\n", freq);
+ dev_dbg(cpu_dai->dev, "I2S MCLK frequency is %uHz. mode: %s, dir: %s\n",
+ freq, STM32_I2S_IS_MASTER(i2s) ? "master" : "slave",
+ dir ? "output" : "input");

- if ((dir == SND_SOC_CLOCK_OUT) && STM32_I2S_IS_MASTER(i2s)) {
- i2s->mclk_rate = freq;
+ /* MCLK generation is available only in master mode */
+ if (dir == SND_SOC_CLOCK_OUT && STM32_I2S_IS_MASTER(i2s)) {
+ if (!i2s->i2smclk) {
+ dev_dbg(cpu_dai->dev, "No MCLK registered\n");
+ return 0;
+ }

- /* Enable master clock if master mode and mclk-fs are set */
- return regmap_update_bits(i2s->regmap, STM32_I2S_CGFR_REG,
- I2S_CGFR_MCKOE, I2S_CGFR_MCKOE);
+ /* Assume shutdown if requested frequency is 0Hz */
+ if (!freq) {
+ /* Release mclk rate only if rate was actually set */
+ if (i2s->mclk_rate) {
+ clk_rate_exclusive_put(i2s->i2smclk);
+ i2s->mclk_rate = 0;
+ }
+ return regmap_update_bits(i2s->regmap,
+ STM32_I2S_CGFR_REG,
+ I2S_CGFR_MCKOE, 0);
+ }
+ /* If master clock is used, set parent clock now */
+ ret = stm32_i2s_set_parent_clock(i2s, freq);
+ if (ret)
+ return ret;
+ ret = clk_set_rate_exclusive(i2s->i2smclk, freq);
+ if (ret) {
+ dev_err(cpu_dai->dev, "Could not set mclk rate\n");
+ return ret;
+ }
+ ret = regmap_update_bits(i2s->regmap, STM32_I2S_CGFR_REG,
+ I2S_CGFR_MCKOE, I2S_CGFR_MCKOE);
+ if (!ret)
+ i2s->mclk_rate = freq;
}

- return 0;
+ return ret;
}

static int stm32_i2s_configure_clock(struct snd_soc_dai *cpu_dai,
@@ -424,11 +661,10 @@ static int stm32_i2s_configure_clock(struct snd_soc_dai *cpu_dai,
{
struct stm32_i2s_data *i2s = snd_soc_dai_get_drvdata(cpu_dai);
unsigned long i2s_clock_rate;
- unsigned int tmp, div, real_div, nb_bits, frame_len;
+ unsigned int nb_bits, frame_len;
unsigned int rate = params_rate(params);
+ u32 cgfr;
int ret;
- u32 cgfr, cgfr_mask;
- bool odd;

if (!(rate % 11025))
clk_set_parent(i2s->i2sclk, i2s->x11kclk);
@@ -449,7 +685,10 @@ static int stm32_i2s_configure_clock(struct snd_soc_dai *cpu_dai,
* dsp mode : div = i2s_clk / (nb_bits x ws)
*/
if (i2s->mclk_rate) {
- tmp = DIV_ROUND_CLOSEST(i2s_clock_rate, i2s->mclk_rate);
+ ret = stm32_i2s_calc_clk_div(i2s, i2s_clock_rate,
+ i2s->mclk_rate);
+ if (ret)
+ return ret;
} else {
frame_len = 32;
if ((i2s->fmt & SND_SOC_DAIFMT_FORMAT_MASK) ==
@@ -462,34 +701,13 @@ static int stm32_i2s_configure_clock(struct snd_soc_dai *cpu_dai,
return ret;

nb_bits = frame_len * ((cgfr & I2S_CGFR_CHLEN) + 1);
- tmp = DIV_ROUND_CLOSEST(i2s_clock_rate, (nb_bits * rate));
- }
-
- /* Check the parity of the divider */
- odd = tmp & 0x1;
-
- /* Compute the div prescaler */
- div = tmp >> 1;
-
- cgfr = I2S_CGFR_I2SDIV_SET(div) | (odd << I2S_CGFR_ODD_SHIFT);
- cgfr_mask = I2S_CGFR_I2SDIV_MASK | I2S_CGFR_ODD;
-
- real_div = ((2 * div) + odd);
- dev_dbg(cpu_dai->dev, "I2S clk: %ld, SCLK: %d\n",
- i2s_clock_rate, rate);
- dev_dbg(cpu_dai->dev, "Divider: 2*%d(div)+%d(odd) = %d\n",
- div, odd, real_div);
-
- if (((div == 1) && odd) || (div > I2S_CGFR_I2SDIV_MAX)) {
- dev_err(cpu_dai->dev, "Wrong divider setting\n");
- return -EINVAL;
+ ret = stm32_i2s_calc_clk_div(i2s, i2s_clock_rate,
+ (nb_bits * rate));
+ if (ret)
+ return ret;
}

- if (!div && !odd)
- dev_warn(cpu_dai->dev, "real divider forced to 1\n");
-
- ret = regmap_update_bits(i2s->regmap, STM32_I2S_CGFR_REG,
- cgfr_mask, cgfr);
+ ret = stm32_i2s_set_clk_div(i2s);
if (ret < 0)
return ret;

@@ -694,9 +912,6 @@ static void stm32_i2s_shutdown(struct snd_pcm_substream *substream,
struct stm32_i2s_data *i2s = snd_soc_dai_get_drvdata(cpu_dai);
unsigned long flags;

- regmap_update_bits(i2s->regmap, STM32_I2S_CGFR_REG,
- I2S_CGFR_MCKOE, (unsigned int)~I2S_CGFR_MCKOE);
-
clk_disable_unprepare(i2s->i2sclk);

spin_lock_irqsave(&i2s->irq_lock, flags);
@@ -861,6 +1076,13 @@ static int stm32_i2s_parse_dt(struct platform_device *pdev,
return PTR_ERR(i2s->x11kclk);
}

+ /* Register mclk provider if requested */
+ if (of_find_property(np, "#clock-cells", NULL)) {
+ ret = stm32_i2s_add_mclk_provider(i2s);
+ if (ret < 0)
+ return ret;
+ }
+
/* Get irqs */
irq = platform_get_irq(pdev, 0);
if (irq < 0)
@@ -906,16 +1128,16 @@ static int stm32_i2s_probe(struct platform_device *pdev)
if (!i2s)
return -ENOMEM;

- ret = stm32_i2s_parse_dt(pdev, i2s);
- if (ret)
- return ret;
-
i2s->pdev = pdev;
i2s->ms_flg = I2S_MS_NOT_SET;
spin_lock_init(&i2s->lock_fd);
spin_lock_init(&i2s->irq_lock);
platform_set_drvdata(pdev, i2s);

+ ret = stm32_i2s_parse_dt(pdev, i2s);
+ if (ret)
+ return ret;
+
ret = stm32_i2s_dais_init(pdev, i2s);
if (ret)
return ret;
--
2.17.1
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