clk: rockchip: fix deadlock possibility in cpuclk

Lockdep reported a possible deadlock between the cpuclk lock and for example
the i2c driver.

       CPU0                    CPU1
       ----                    ----
  lock(clk_lock);
                               local_irq_disable();
                               lock(&(&i2c->lock)->rlock);
                               lock(clk_lock);
  <Interrupt>
    lock(&(&i2c->lock)->rlock);

 *** DEADLOCK ***

The generic clock-types of the core ccf already use spin_lock_irqsave when
touching clock registers, so do the same for the cpuclk.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Michael Turquette <mturquette@linaro.org>
[mturquette@linaro.org: removed initialization of "flags"]

drivers/clk/rockchip/clk-cpu.c

@@ -124,10 +124,11 @@ static int rockchip_cpuclk_pre_rate_change(struct rockchip_cpuclk *cpuclk,
 {
 	const struct rockchip_cpuclk_reg_data *reg_data = cpuclk->reg_data;
 	unsigned long alt_prate, alt_div;
+	unsigned long flags;
 
 	alt_prate = clk_get_rate(cpuclk->alt_parent);
 
-	spin_lock(cpuclk->lock);
+	spin_lock_irqsave(cpuclk->lock, flags);
 
 	/*
 	 * If the old parent clock speed is less than the clock speed
@@ -164,7 +165,7 @@ static int rockchip_cpuclk_pre_rate_change(struct rockchip_cpuclk *cpuclk,
 			cpuclk->reg_base + reg_data->core_reg);
 	}
 
-	spin_unlock(cpuclk->lock);
+	spin_unlock_irqrestore(cpuclk->lock, flags);
 	return 0;
 }
 
@@ -173,6 +174,7 @@ static int rockchip_cpuclk_post_rate_change(struct rockchip_cpuclk *cpuclk,
 {
 	const struct rockchip_cpuclk_reg_data *reg_data = cpuclk->reg_data;
 	const struct rockchip_cpuclk_rate_table *rate;
+	unsigned long flags;
 
 	rate = rockchip_get_cpuclk_settings(cpuclk, ndata->new_rate);
 	if (!rate) {
@@ -181,7 +183,7 @@ static int rockchip_cpuclk_post_rate_change(struct rockchip_cpuclk *cpuclk,
 		return -EINVAL;
 	}
 
-	spin_lock(cpuclk->lock);
+	spin_lock_irqsave(cpuclk->lock, flags);
 
 	if (ndata->old_rate < ndata->new_rate)
 		rockchip_cpuclk_set_dividers(cpuclk, rate);
@@ -201,7 +203,7 @@ static int rockchip_cpuclk_post_rate_change(struct rockchip_cpuclk *cpuclk,
 	if (ndata->old_rate > ndata->new_rate)
 		rockchip_cpuclk_set_dividers(cpuclk, rate);
 
-	spin_unlock(cpuclk->lock);
+	spin_unlock_irqrestore(cpuclk->lock, flags);
 	return 0;
 }