[PATCH] iio: adc: vf610: Avoid division by zero

[Fabio Estevam <fabio.estevam@freescale.com>]

When the 'adck-max-frequency' property is not passed in device tree,
the following division by zero is seen:

[    2.196814] Hardware name: Freescale i.MX6 SoloX (Device Tree)
[    2.202652] Backtrace: 
[    2.205156] [<c0013600>] (dump_backtrace) from [<c001379c>] (show_stack+0x18/0x1c)
[    2.212730]  r6:ef138410 r5:00000000 r4:00000000 r3:00000000
[    2.218494] [<c0013784>] (show_stack) from [<c02d8220>] (dump_stack+0x88/0xa4)
[    2.225756] [<c02d8198>] (dump_stack) from [<c001346c>] (__div0+0x18/0x20)
[    2.232636]  r5:00000001 r4:eeb0a800
[    2.236286] [<c0013454>] (__div0) from [<c02d6be4>] (Ldiv0+0x8/0x10)
[    2.242657] [<c0574574>] (vf610_adc_probe) from [<c03c9274>] (platform_drv_probe+0x58/0xb4)

Provide a sane adck_rate default value that can be used in normal,
high-speed and low-power modes in the case of 'adck-max-frequency' property
being absent.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
---
 drivers/iio/adc/vf610_adc.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/iio/adc/vf610_adc.c b/drivers/iio/adc/vf610_adc.c
index 599cde3..424fd69 100644
--- a/drivers/iio/adc/vf610_adc.c
+++ b/drivers/iio/adc/vf610_adc.c
@@ -105,6 +105,7 @@
 #define VF610_ADC_TIMEOUT		msecs_to_jiffies(100)
 
 #define DEFAULT_SAMPLE_TIME		1000
+#define ADCK_RATE_MAX_DEFAULT		20000000
 
 enum clk_sel {
 	VF610_ADCIOC_BUSCLK_SET,
@@ -195,6 +196,7 @@ static inline void vf610_adc_calculate_rates(struct vf610_adc *info)
 	} else {
 		/* fall-back value using a safe divisor */
 		adc_feature->clk_div = 8;
+		adck_rate = ADCK_RATE_MAX_DEFAULT;
 	}
 
 	/*
-- 
1.9.1