[PATCHv4 6/7] hwspinlock/omap: enable module before reading SYSSTATUS register
From: Suman Anna <hidden>
Date: 2014-01-14 00:21:22
Also in:
linux-devicetree, linux-omap, lkml
Subsystem:
hardware spinlock core, omap hardware spinlock support, the rest · Maintainers:
Bjorn Andersson, Linus Torvalds
The number of hwspinlocks are determined based on the value read from the IP block's SYSSTATUS register. However, the module may not be enabled and clocked, and the read may result in a bus error. This particular issue is seen rather easily on AM33XX, since the module wakeup is software controlled, and it is disabled out of reset. Make sure the module is enabled and clocked before reading the SYSSTATUS register. Signed-off-by: Suman Anna <redacted> --- drivers/hwspinlock/omap_hwspinlock.c | 21 ++++++++++++++------- 1 file changed, 14 insertions(+), 7 deletions(-)
diff --git a/drivers/hwspinlock/omap_hwspinlock.c b/drivers/hwspinlock/omap_hwspinlock.c
index 9f56fb2..194886e 100644
--- a/drivers/hwspinlock/omap_hwspinlock.c
+++ b/drivers/hwspinlock/omap_hwspinlock.c@@ -101,10 +101,23 @@ static int omap_hwspinlock_probe(struct platform_device *pdev) if (!io_base) return -ENOMEM; + /* + * make sure the module is enabled and clocked before reading + * the module SYSSTATUS register + */ + pm_runtime_enable(&pdev->dev); + pm_runtime_get_sync(&pdev->dev); + /* Determine number of locks */ i = readl(io_base + SYSSTATUS_OFFSET); i >>= SPINLOCK_NUMLOCKS_BIT_OFFSET; + /* + * runtime PM will make sure the clock of this module is + * enabled again iff at least one lock is requested + */ + pm_runtime_put(&pdev->dev); + /* one of the four lsb's must be set, and nothing else */ if (hweight_long(i & 0xf) != 1 || i > 8) { ret = -EINVAL;
@@ -124,12 +137,6 @@ static int omap_hwspinlock_probe(struct platform_device *pdev) for (i = 0, hwlock = &bank->lock[0]; i < num_locks; i++, hwlock++) hwlock->priv = io_base + LOCK_BASE_OFFSET + sizeof(u32) * i; - /* - * runtime PM will make sure the clock of this module is - * enabled iff at least one lock is requested - */ - pm_runtime_enable(&pdev->dev); - ret = hwspin_lock_register(bank, &pdev->dev, &omap_hwspinlock_ops, base_id, num_locks); if (ret)
@@ -138,9 +145,9 @@ static int omap_hwspinlock_probe(struct platform_device *pdev) return 0; reg_fail: - pm_runtime_disable(&pdev->dev); kfree(bank); iounmap_base: + pm_runtime_disable(&pdev->dev); iounmap(io_base); return ret; }
--
1.8.4.3