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USB: c67x00: add proper delays to HPI read/write

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According to CY7C67300 specification HPI read and write cycle duration
Tcyc must be at least 6T long, where T is 1/48MHz, which is 125ns.
Without this delay fast host processor cannot write to chip registers.
Add proper ndelay to hpi_{read,write}_reg.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Acked-by: Peter Korsgaard <peter@korsgaard.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Max Filippov 2013-12-25 16:01:30 +04:00 committed by Greg Kroah-Hartman
parent 543d7784b0
commit 8f668fbbd5
1 changed files with 10 additions and 0 deletions
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10
drivers/usb/c67x00/c67x00-ll-hpi.c
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@ -22,6 +22,7 @@
*/
#include <asm/byteorder.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/jiffies.h>
#include <linux/usb/c67x00.h>
@ -73,13 +74,22 @@ struct c67x00_lcp_int_data {
#define HPI_ADDR 2
#define HPI_STATUS 3
/*
* According to CY7C67300 specification (tables 140 and 141) HPI read and
* write cycle duration Tcyc must be at least 6T long, where T is 1/48MHz,
* which is 125ns.
*/
#define HPI_T_CYC_NS 125
static inline u16 hpi_read_reg(struct c67x00_device *dev, int reg)
{
ndelay(HPI_T_CYC_NS);
return __raw_readw(dev->hpi.base + reg * dev->hpi.regstep);
}
static inline void hpi_write_reg(struct c67x00_device *dev, int reg, u16 value)
{
ndelay(HPI_T_CYC_NS);
__raw_writew(value, dev->hpi.base + reg * dev->hpi.regstep);
}