ARM: mx5: fix clock usage for suspend

While suspending, we're enabling a clock in ->suspend() but we're in atomic
context, leading to this :

[30803.667305] PM: late suspend of devices complete after 1.237 msecs
[30803.667449] BUG: sleeping function called from invalid context at kernel/mutex.c:271
[30803.667464] in_atomic(): 0, irqs_disabled(): 128, pid: 4941, name: pm-suspend
[30803.667474] INFO: lockdep is turned off.
[30803.667483] irq event stamp: 0
[30803.667489] hardirqs last  enabled at (0): [<  (null)>]   (null)
[30803.667503] hardirqs last disabled at (0): [<c001e4a8>] copy_process.part.48+0x1e0/0xa7c
[30803.667543] softirqs last  enabled at (0): [<c001e4a8>] copy_process.part.48+0x1e0/0xa7c
[30803.667562] softirqs last disabled at (0): [<  (null)>]   (null)
[30803.667574] Backtrace:
[30803.667611] [<c0010e00>] (dump_backtrace+0x0/0x110) from [<c0424c00>] (dump_stack+0x18/0x1c)
[30803.667624]  r6:00000000 r5:00000000 r4:d9648000 r3:d9648000
[30803.667652] [<c0424be8>] (dump_stack+0x0/0x1c) from [<c0424eec>] (__might_sleep.part.101+0x90/0xa8)
[30803.667673] [<c0424e5c>] (__might_sleep.part.101+0x0/0xa8) from [<c001a5c4>] (__might_sleep+0x80/0x94)
[30803.667686]  r4:c05d58c0
[30803.667705] [<c001a544>] (__might_sleep+0x0/0x94) from [<c043230c>] (mutex_lock_nested+0x2c/0x30c)
[30803.667735] [<c04322e0>] (mutex_lock_nested+0x0/0x30c) from [<c0017834>] (clk_enable+0x28/0x50)
[30803.667747]  r8:c0438464 r7:00000003 r6:00000000 r5:00000000 r4:c05d2e98
[30803.667780] [<c001780c>] (clk_enable+0x0/0x50) from [<c0017260>] (mx5_suspend_enter+0x1c/0x98)
[30803.667792]  r4:00000003 r3:c060dfe0
[30803.667821] [<c0017244>] (mx5_suspend_enter+0x0/0x98) from [<c0059b48>] (suspend_enter+0xec/0x15c)
[30803.667833]  r4:00000003 r3:c0017244
[30803.667856] [<c0059a5c>] (suspend_enter+0x0/0x15c) from [<c0059c4c>] (suspend_devices_and_enter+0x94/0x130)
[30803.667868]  r6:00000000 r5:00000003 r4:c0c0af00 r3:00002710
[30803.667897] [<c0059bb8>] (suspend_devices_and_enter+0x0/0x130) from [<c0059db0>] (enter_state+0xc8/0x130)
[30803.667909]  r6:00000000 r5:00000003 r4:c05286e4
[30803.667934] [<c0059ce8>] (enter_state+0x0/0x130) from [<c00592d4>] (state_store+0xac/0xc0)
[30803.667945]  r6:00000003 r5:00000003 r4:df39d000 r3:00000003
[30803.667978] [<c0059228>] (state_store+0x0/0xc0) from [<c01b0100>] (kobj_attr_store+0x1c/0x28)
[30803.668009] [<c01b00e4>] (kobj_attr_store+0x0/0x28) from [<c00e435c>] (sysfs_write_file+0x88/0xbc)
[30803.668032] [<c00e42d4>] (sysfs_write_file+0x0/0xbc) from [<c0091fa0>] (vfs_write+0xbc/0x138)
[30803.668051] [<c0091ee4>] (vfs_write+0x0/0x138) from [<c0092204>] (sys_write+0x44/0x70)
[30803.668062]  r8:00000000 r7:00000004 r6:00000003 r5:002694d0 r4:d966acc0
[30803.668094] [<c00921c0>] (sys_write+0x0/0x70) from [<c000db00>] (ret_fast_syscall+0x0/0x3c)
[30803.668106]  r9:d9648000 r8:c000dcc4 r6:00000001 r5:002694d0 r4:00000003
[30803.669927] PM: early resume of devices complete after 0.972 msecs

Just move the clk_enable/disable in ->prepare() and ->finish()
Signed-off-by: Arnaud Patard <arnaud.patard@rtp-net.org>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>

arch/arm/mach-mx5/pm-imx5.c

@@ -19,9 +19,13 @@
 
 static struct clk *gpc_dvfs_clk;
 
+static int mx5_suspend_prepare(void)
+{
+	return clk_enable(gpc_dvfs_clk);
+}
+
 static int mx5_suspend_enter(suspend_state_t state)
 {
-	clk_enable(gpc_dvfs_clk);
 	switch (state) {
 	case PM_SUSPEND_MEM:
 		mx5_cpu_lp_set(STOP_POWER_OFF);
@@ -42,11 +46,14 @@ static int mx5_suspend_enter(suspend_state_t state)
 		__raw_writel(0, MXC_SRPG_EMPGC1_SRPGCR);
 	}
 	cpu_do_idle();
-	clk_disable(gpc_dvfs_clk);
-
 	return 0;
 }
 
+static void mx5_suspend_finish(void)
+{
+	clk_disable(gpc_dvfs_clk);
+}
+
 static int mx5_pm_valid(suspend_state_t state)
 {
 	return (state > PM_SUSPEND_ON && state <= PM_SUSPEND_MAX);
@@ -54,7 +61,9 @@ static int mx5_pm_valid(suspend_state_t state)
 
 static const struct platform_suspend_ops mx5_suspend_ops = {
 	.valid = mx5_pm_valid,
+	.prepare = mx5_suspend_prepare,
 	.enter = mx5_suspend_enter,
+	.finish = mx5_suspend_finish,
 };
 
 static int __init mx5_pm_init(void)