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 eef873db3d48..113c2466c86a 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 f2401a831f99..e5842e30e534 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;
         }