ASoC: fsl_ssi: serialize AC'97 register access operations
AC'97 register access operations (both read and write) on SSI use a one, shared set of SSI registers for AC'97 register address and data. This means that only one such access is possible at a time and so all these operations need to be serialized. Since an AC'97 register access operation in this driver takes 100us+ let's use a mutex for this. Use this opportunity to also change a default value returned from AC'97 register read function from -1 to 0, since that's what AC'97 specs require to be returned when unknown / undefined registers are read. Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name> Signed-off-by: Mark Brown <broonie@kernel.org>
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@ -38,6 +38,7 @@
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#include <linux/ctype.h>
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#include <linux/device.h>
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#include <linux/delay.h>
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#include <linux/mutex.h>
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#include <linux/slab.h>
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#include <linux/spinlock.h>
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#include <linux/of.h>
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@ -265,6 +266,8 @@ struct fsl_ssi_private {
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u32 fifo_watermark;
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u32 dma_maxburst;
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struct mutex ac97_reg_lock;
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};
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/*
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@ -1260,11 +1263,13 @@ static void fsl_ssi_ac97_write(struct snd_ac97 *ac97, unsigned short reg,
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if (reg > 0x7f)
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return;
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mutex_lock(&fsl_ac97_data->ac97_reg_lock);
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ret = clk_prepare_enable(fsl_ac97_data->clk);
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if (ret) {
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pr_err("ac97 write clk_prepare_enable failed: %d\n",
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ret);
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return;
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goto ret_unlock;
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}
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lreg = reg << 12;
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@ -1278,6 +1283,9 @@ static void fsl_ssi_ac97_write(struct snd_ac97 *ac97, unsigned short reg,
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udelay(100);
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clk_disable_unprepare(fsl_ac97_data->clk);
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ret_unlock:
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mutex_unlock(&fsl_ac97_data->ac97_reg_lock);
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}
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static unsigned short fsl_ssi_ac97_read(struct snd_ac97 *ac97,
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@ -1285,16 +1293,18 @@ static unsigned short fsl_ssi_ac97_read(struct snd_ac97 *ac97,
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{
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struct regmap *regs = fsl_ac97_data->regs;
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unsigned short val = -1;
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unsigned short val = 0;
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u32 reg_val;
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unsigned int lreg;
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int ret;
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mutex_lock(&fsl_ac97_data->ac97_reg_lock);
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ret = clk_prepare_enable(fsl_ac97_data->clk);
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if (ret) {
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pr_err("ac97 read clk_prepare_enable failed: %d\n",
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ret);
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return -1;
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goto ret_unlock;
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}
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lreg = (reg & 0x7f) << 12;
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@ -1309,6 +1319,8 @@ static unsigned short fsl_ssi_ac97_read(struct snd_ac97 *ac97,
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clk_disable_unprepare(fsl_ac97_data->clk);
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ret_unlock:
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mutex_unlock(&fsl_ac97_data->ac97_reg_lock);
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return val;
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}
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@ -1569,6 +1581,7 @@ static int fsl_ssi_probe(struct platform_device *pdev)
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}
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if (fsl_ssi_is_ac97(ssi_private)) {
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mutex_init(&ssi_private->ac97_reg_lock);
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ret = snd_soc_set_ac97_ops_of_reset(&fsl_ssi_ac97_ops, pdev);
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if (ret) {
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dev_err(&pdev->dev, "could not set AC'97 ops\n");
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@ -1663,6 +1676,9 @@ error_asoc_register:
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snd_soc_set_ac97_ops(NULL);
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error_ac97_ops:
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if (fsl_ssi_is_ac97(ssi_private))
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mutex_destroy(&ssi_private->ac97_reg_lock);
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if (ssi_private->soc->imx)
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fsl_ssi_imx_clean(pdev, ssi_private);
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@ -1681,8 +1697,10 @@ static int fsl_ssi_remove(struct platform_device *pdev)
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if (ssi_private->soc->imx)
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fsl_ssi_imx_clean(pdev, ssi_private);
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if (fsl_ssi_is_ac97(ssi_private))
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if (fsl_ssi_is_ac97(ssi_private)) {
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snd_soc_set_ac97_ops(NULL);
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mutex_destroy(&ssi_private->ac97_reg_lock);
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}
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return 0;
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}
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