spi: mediatek: add no_need_unprepare support

This patch add no_need_unprepare support for spi, if spi src clk is
MAIN PLL, it can keep the clk_prepare and will not cause low power
issue. So we no need do clk_prepare/clk_unprepare in runtime pm,
and it will get better performance, because clk_prepare has called
mutex lock.
In the same way,
clk_get_rate also has called mutex lock, so we moved it to spi_probe.

Signed-off-by: Mason Zhang <Mason.Zhang@mediatek.com>
Link: https://lore.kernel.org/r/20210629100814.21402-1-mason.zhang@mediatek.com
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-mt65xx.c

@@ -90,6 +90,8 @@ struct mtk_spi_compatible {
 	bool enhance_timing;
 	/* some IC support DMA addr extension */
 	bool dma_ext;
+	/* some IC no need unprepare SPI clk */
+	bool no_need_unprepare;
 };
 
 struct mtk_spi {
@@ -104,6 +106,7 @@ struct mtk_spi {
 	struct scatterlist *tx_sgl, *rx_sgl;
 	u32 tx_sgl_len, rx_sgl_len;
 	const struct mtk_spi_compatible *dev_comp;
+	u32 spi_clk_hz;
 };
 
 static const struct mtk_spi_compatible mtk_common_compat;
@@ -135,6 +138,14 @@ static const struct mtk_spi_compatible mt8183_compat = {
 	.enhance_timing = true,
 };
 
+static const struct mtk_spi_compatible mt6893_compat = {
+	.need_pad_sel = true,
+	.must_tx = true,
+	.enhance_timing = true,
+	.dma_ext = true,
+	.no_need_unprepare = true,
+};
+
 /*
  * A piece of default chip info unless the platform
  * supplies it.
@@ -174,6 +185,9 @@ static const struct of_device_id mtk_spi_of_match[] = {
 	{ .compatible = "mediatek,mt8192-spi",
 		.data = (void *)&mt6765_compat,
 	},
+	{ .compatible = "mediatek,mt6893-spi",
+		.data = (void *)&mt6893_compat,
+	},
 	{}
 };
 MODULE_DEVICE_TABLE(of, mtk_spi_of_match);
@@ -287,12 +301,11 @@ static void mtk_spi_set_cs(struct spi_device *spi, bool enable)
 static void mtk_spi_prepare_transfer(struct spi_master *master,
 				     struct spi_transfer *xfer)
 {
-	u32 spi_clk_hz, div, sck_time, reg_val;
+	u32 div, sck_time, reg_val;
 	struct mtk_spi *mdata = spi_master_get_devdata(master);
 
-	spi_clk_hz = clk_get_rate(mdata->spi_clk);
-	if (xfer->speed_hz < spi_clk_hz / 2)
-		div = DIV_ROUND_UP(spi_clk_hz, xfer->speed_hz);
+	if (xfer->speed_hz < mdata->spi_clk_hz / 2)
+		div = DIV_ROUND_UP(mdata->spi_clk_hz, xfer->speed_hz);
 	else
 		div = 1;
 
@@ -789,7 +802,12 @@ static int mtk_spi_probe(struct platform_device *pdev)
 		goto err_put_master;
 	}
 
-	clk_disable_unprepare(mdata->spi_clk);
+	mdata->spi_clk_hz = clk_get_rate(mdata->spi_clk);
+
+	if (mdata->dev_comp->no_need_unprepare)
+		clk_disable(mdata->spi_clk);
+	else
+		clk_disable_unprepare(mdata->spi_clk);
 
 	pm_runtime_enable(&pdev->dev);
 
@@ -857,6 +875,9 @@ static int mtk_spi_remove(struct platform_device *pdev)
 
 	mtk_spi_reset(mdata);
 
+	if (mdata->dev_comp->no_need_unprepare)
+		clk_unprepare(mdata->spi_clk);
+
 	return 0;
 }
 
@@ -905,7 +926,10 @@ static int mtk_spi_runtime_suspend(struct device *dev)
 	struct spi_master *master = dev_get_drvdata(dev);
 	struct mtk_spi *mdata = spi_master_get_devdata(master);
 
-	clk_disable_unprepare(mdata->spi_clk);
+	if (mdata->dev_comp->no_need_unprepare)
+		clk_disable(mdata->spi_clk);
+	else
+		clk_disable_unprepare(mdata->spi_clk);
 
 	return 0;
 }
@@ -916,7 +940,10 @@ static int mtk_spi_runtime_resume(struct device *dev)
 	struct mtk_spi *mdata = spi_master_get_devdata(master);
 	int ret;
 
-	ret = clk_prepare_enable(mdata->spi_clk);
+	if (mdata->dev_comp->no_need_unprepare)
+		ret = clk_enable(mdata->spi_clk);
+	else
+		ret = clk_prepare_enable(mdata->spi_clk);
 	if (ret < 0) {
 		dev_err(dev, "failed to enable spi_clk (%d)\n", ret);
 		return ret;