[PATCH 4.6 077/100] clk: bcm2835: add locking to pll*_on/off methods

[Greg Kroah-Hartman]

4.6-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Martin Sperl <kernel@xxxxxxxxxxxxxxxx>

commit ec36a5c6682fdd5328abf15c3c67281bed0241d7 upstream.

Add missing locking to:
* bcm2835_pll_divider_on
* bcm2835_pll_divider_off
to protect the read modify write cycle for the
register access protecting both cm_reg and a2w_reg
registers.

Fixes: 41691b8862e2 ("clk: bcm2835: Add support for programming the
audio domain clocks")

Signed-off-by: Martin Sperl <kernel@xxxxxxxxxxxxxxxx>
Signed-off-by: Eric Anholt <eric@xxxxxxxxxx>
Reviewed-by: Eric Anholt <eric@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/clk/bcm/clk-bcm2835.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/clk/bcm/clk-bcm2835.c
+++ b/drivers/clk/bcm/clk-bcm2835.c
@@ -1079,10 +1079,12 @@ static void bcm2835_pll_divider_off(stru
 	struct bcm2835_cprman *cprman = divider->cprman;
 	const struct bcm2835_pll_divider_data *data = divider->data;
 
+	spin_lock(&cprman->regs_lock);
 	cprman_write(cprman, data->cm_reg,
 		     (cprman_read(cprman, data->cm_reg) &
 		      ~data->load_mask) | data->hold_mask);
 	cprman_write(cprman, data->a2w_reg, A2W_PLL_CHANNEL_DISABLE);
+	spin_unlock(&cprman->regs_lock);
 }
 
 static int bcm2835_pll_divider_on(struct clk_hw *hw)
@@ -1091,12 +1093,14 @@ static int bcm2835_pll_divider_on(struct
 	struct bcm2835_cprman *cprman = divider->cprman;
 	const struct bcm2835_pll_divider_data *data = divider->data;
 
+	spin_lock(&cprman->regs_lock);
 	cprman_write(cprman, data->a2w_reg,
 		     cprman_read(cprman, data->a2w_reg) &
 		     ~A2W_PLL_CHANNEL_DISABLE);
 
 	cprman_write(cprman, data->cm_reg,
 		     cprman_read(cprman, data->cm_reg) & ~data->hold_mask);
+	spin_unlock(&cprman->regs_lock);
 
 	return 0;
 }