[PATCH 4/9] mmc: bcm2835: Introduce proper clock handling

[Stefan Wahren <wahrenst@gmx.net>]

The custom sdhost controller on BCM2835 is feed by the critical VPU clock.
In preparation for PM suspend/resume support, add a proper clock handling
to the driver like in the other clock consumers (e.g. I2C).

Move the clock handling behind mmc_of_parse(), because it could return
with -EPROBE_DEFER and we want to minimize potential clock operation during
boot phase.

Signed-off-by: Stefan Wahren <wahrenst@gmx.net>
---
 drivers/mmc/host/bcm2835.c | 29 ++++++++++++++++++-----------
 1 file changed, 18 insertions(+), 11 deletions(-)

diff --git a/drivers/mmc/host/bcm2835.c b/drivers/mmc/host/bcm2835.c
index 3d3eda5a337c..107666b7c1c8 100644
--- a/drivers/mmc/host/bcm2835.c
+++ b/drivers/mmc/host/bcm2835.c
@@ -148,6 +148,7 @@ struct bcm2835_host {
 	void __iomem		*ioaddr;
 	u32			phys_addr;

+	struct clk		*clk;
 	struct platform_device	*pdev;

 	unsigned int		clock;		/* Current clock speed */
@@ -1345,7 +1346,6 @@ static int bcm2835_add_host(struct bcm2835_host *host)
 static int bcm2835_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
-	struct clk *clk;
 	struct bcm2835_host *host;
 	struct mmc_host *mmc;
 	const __be32 *regaddr_p;
@@ -1393,15 +1393,6 @@ static int bcm2835_probe(struct platform_device *pdev)
 		/* Ignore errors to fall back to PIO mode */
 	}

-
-	clk = devm_clk_get(dev, NULL);
-	if (IS_ERR(clk)) {
-		ret = dev_err_probe(dev, PTR_ERR(clk), "could not get clk\n");
-		goto err;
-	}
-
-	host->max_clk = clk_get_rate(clk);
-
 	host->irq = platform_get_irq(pdev, 0);
 	if (host->irq < 0) {
 		ret = host->irq;
@@ -1412,16 +1403,30 @@ static int bcm2835_probe(struct platform_device *pdev)
 	if (ret)
 		goto err;

-	ret = bcm2835_add_host(host);
+	host->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(host->clk)) {
+		ret = dev_err_probe(dev, PTR_ERR(host->clk), "could not get clk\n");
+		goto err;
+	}
+
+	ret = clk_prepare_enable(host->clk);
 	if (ret)
 		goto err;

+	host->max_clk = clk_get_rate(host->clk);
+
+	ret = bcm2835_add_host(host);
+	if (ret)
+		goto err_clk;
+
 	platform_set_drvdata(pdev, host);

 	dev_dbg(dev, "%s -> OK\n", __func__);

 	return 0;

+err_clk:
+	clk_disable_unprepare(host->clk);
 err:
 	dev_dbg(dev, "%s -> err %d\n", __func__, ret);
 	if (host->dma_chan_rxtx)
@@ -1445,6 +1450,8 @@ static void bcm2835_remove(struct platform_device *pdev)
 	cancel_work_sync(&host->dma_work);
 	cancel_delayed_work_sync(&host->timeout_work);

+	clk_disable_unprepare(host->clk);
+
 	if (host->dma_chan_rxtx)
 		dma_release_channel(host->dma_chan_rxtx);

--
2.34.1