ARM: OMAP: Fix McBSP spin_lock deadlock

A spin_lock deadlock will occur when omap_mcbsp_request() is invoked.

omap_mcbsp_request()
\- clk_enable(mcbsp->clk)         [takes and holds clockfw_lock]
    \- omap2_clk_enable()
       \- _omap2_clk_enable()
           \- omap_mcbsp_clk_enable()
              \- clk_enable(child clock)   [tries for clockfw_lock again]

mcbsp_clk is a virtual clock and it comprises several child clocks. when
enable mcbsp_clk in omap_mcbsp_request(), the enable function of mcbsp_clk
will enable its child clocks, then the deadlock occurs.

The solution is to remove the virtual clock and enable these child clocks in
omap_mcbsp_request() directly.

Signed-off-by: Stanley.Miao <stanley.miao@windriver.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

2 files changed, 43 insertions, 15 deletions

diff --git a/arch/arm/plat-omap/include/mach/mcbsp.h b/arch/arm/plat-omap/include/mach/mcbsp.h
index eef873db3d4..113c2466c86 100644
--- a/arch/arm/plat-omap/include/mach/mcbsp.h
+++ b/arch/arm/plat-omap/include/mach/mcbsp.h
@@ -344,7 +344,8 @@ struct omap_mcbsp_platform_data {
 	u8 dma_rx_sync, dma_tx_sync;
 	u16 rx_irq, tx_irq;
 	struct omap_mcbsp_ops *ops;
-	char const *clk_name;
+	char const **clk_names;
+	int num_clks;
 };
 
 struct omap_mcbsp {
@@ -376,7 +377,8 @@ struct omap_mcbsp {
 	/* Protect the field .free, while checking if the mcbsp is in use */
 	spinlock_t lock;
 	struct omap_mcbsp_platform_data *pdata;
-	struct clk *clk;
+	struct clk **clks;
+	int num_clks;
 };
 extern struct omap_mcbsp **mcbsp_ptr;
 extern int omap_mcbsp_count;
diff --git a/arch/arm/plat-omap/mcbsp.c b/arch/arm/plat-omap/mcbsp.c
index f2401a831f9..e5842e30e53 100644
--- a/arch/arm/plat-omap/mcbsp.c
+++ b/arch/arm/plat-omap/mcbsp.c
@@ -214,6 +214,7 @@ EXPORT_SYMBOL(omap_mcbsp_set_io_type);
 int omap_mcbsp_request(unsigned int id)
 {
 	struct omap_mcbsp *mcbsp;
+	int i;
 	int err;
 
 	if (!omap_mcbsp_check_valid_id(id)) {
@@ -225,7 +226,8 @@ int omap_mcbsp_request(unsigned int id)
 	if (mcbsp->pdata && mcbsp->pdata->ops && mcbsp->pdata->ops->request)
 		mcbsp->pdata->ops->request(id);
 
-	clk_enable(mcbsp->clk);
+	for (i = 0; i < mcbsp->num_clks; i++)
+		clk_enable(mcbsp->clks[i]);
 
 	spin_lock(&mcbsp->lock);
 	if (!mcbsp->free) {
@@ -276,6 +278,7 @@ EXPORT_SYMBOL(omap_mcbsp_request);
 void omap_mcbsp_free(unsigned int id)
 {
 	struct omap_mcbsp *mcbsp;
+	int i;
 
 	if (!omap_mcbsp_check_valid_id(id)) {
 		printk(KERN_ERR "%s: Invalid id (%d)\n", __func__, id + 1);
@@ -286,7 +289,8 @@ void omap_mcbsp_free(unsigned int id)
 	if (mcbsp->pdata && mcbsp->pdata->ops && mcbsp->pdata->ops->free)
 		mcbsp->pdata->ops->free(id);
 
-	clk_disable(mcbsp->clk);
+	for (i = mcbsp->num_clks - 1; i >= 0; i--)
+		clk_disable(mcbsp->clks[i]);
 
 	spin_lock(&mcbsp->lock);
 	if (mcbsp->free) {
@@ -872,6 +876,7 @@ static int __devinit omap_mcbsp_probe(struct platform_device *pdev)
 	struct omap_mcbsp_platform_data *pdata = pdev->dev.platform_data;
 	struct omap_mcbsp *mcbsp;
 	int id = pdev->id - 1;
+	int i;
 	int ret = 0;
 
 	if (!pdata) {
@@ -916,14 +921,25 @@ static int __devinit omap_mcbsp_probe(struct platform_device *pdev)
 	mcbsp->dma_rx_sync = pdata->dma_rx_sync;
 	mcbsp->dma_tx_sync = pdata->dma_tx_sync;
 
-	if (pdata->clk_name)
-		mcbsp->clk = clk_get(&pdev->dev, pdata->clk_name);
-	if (IS_ERR(mcbsp->clk)) {
-		dev_err(&pdev->dev,
-			"Invalid clock configuration for McBSP%d.\n",
-			mcbsp->id);
-		ret = PTR_ERR(mcbsp->clk);
-		goto err_clk;
+	if (pdata->num_clks) {
+		mcbsp->num_clks = pdata->num_clks;
+		mcbsp->clks = kzalloc(mcbsp->num_clks * sizeof(struct clk *),
+					GFP_KERNEL);
+		if (!mcbsp->clks) {
+			ret = -ENOMEM;
+			goto exit;
+		}
+		for (i = 0; i < mcbsp->num_clks; i++) {
+			mcbsp->clks[i] = clk_get(&pdev->dev, pdata->clk_names[i]);
+			if (IS_ERR(mcbsp->clks[i])) {
+				dev_err(&pdev->dev,
+					"Invalid %s configuration for McBSP%d.\n",
+					pdata->clk_names[i], mcbsp->id);
+				ret = PTR_ERR(mcbsp->clks[i]);
+				goto err_clk;
+			}
+		}
+
 	}
 
 	mcbsp->pdata = pdata;
@@ -932,6 +948,9 @@ static int __devinit omap_mcbsp_probe(struct platform_device *pdev)
 	return 0;
 
 err_clk:
+	while (i--)
+		clk_put(mcbsp->clks[i]);
+	kfree(mcbsp->clks);
 	iounmap(mcbsp->io_base);
 err_ioremap:
 	mcbsp->free = 0;
@@ -942,6 +961,7 @@ exit:
 static int __devexit omap_mcbsp_remove(struct platform_device *pdev)
 {
 	struct omap_mcbsp *mcbsp = platform_get_drvdata(pdev);
+	int i;
 
 	platform_set_drvdata(pdev, NULL);
 	if (mcbsp) {
@@ -950,12 +970,18 @@ static int __devexit omap_mcbsp_remove(struct platform_device *pdev)
 				mcbsp->pdata->ops->free)
 			mcbsp->pdata->ops->free(mcbsp->id);
 
-		clk_disable(mcbsp->clk);
-		clk_put(mcbsp->clk);
+		for (i = mcbsp->num_clks - 1; i >= 0; i--) {
+			clk_disable(mcbsp->clks[i]);
+			clk_put(mcbsp->clks[i]);
+		}
 
 		iounmap(mcbsp->io_base);
 
-		mcbsp->clk = NULL;
+		if (mcbsp->num_clks) {
+			kfree(mcbsp->clks);
+			mcbsp->clks = NULL;
+			mcbsp->num_clks = 0;
+		}
 		mcbsp->free = 0;
 		mcbsp->dev = NULL;
 	}