OMAP2+: hwmod: upgrade per-hwmod mutex to a spinlock
Change the per-hwmod mutex to a spinlock. (The per-hwmod lock serializes most post-initialization hwmod operations such as enable, idle, and shutdown.) Spinlocks are needed, because in some cases, hwmods must be enabled from timer interrupt disabled-context, such as an ISR. The current use-case that is driving this is the OMAP GPIO block ISR: it can trigger interrupts even with its clocks disabled, but these clocks are needed for register accesses in the ISR to succeed. This patch also effectively reverts commit 84824022 - this patch makes _omap_hwmod_enable() and _omap_hwmod_init() static, renames them back to _enable() and _idle(), and changes their callers to call the spinlocking versions. Previously, since omap_hwmod_{enable,init}() attempted to take mutexes, these functions could not be called while the timer interrupt was disabled; but now that the functions use spinlocks and save and restore the IRQ state, it is appropriate to call them directly. Kevin Hilman <khilman@deeprootsystems.com> originally proposed this patch - thanks Kevin. Signed-off-by: Paul Walmsley <paul@pwsan.com> Cc: Kevin Hilman <khilman@deeprootsystems.com> Cc: Benoît Cousson <b-cousson@ti.com>
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