57 строки
1.6 KiB
C
57 строки
1.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
|
|
/*
|
|
* Copyright 2012 DENX Software Engineering, GmbH
|
|
*
|
|
* Pulled from code:
|
|
* Portions copyright (C) 2003 Russell King, PXA MMCI Driver
|
|
* Portions copyright (C) 2004-2005 Pierre Ossman, W83L51xD SD/MMC driver
|
|
*
|
|
* Copyright 2008 Embedded Alley Solutions, Inc.
|
|
* Copyright 2009-2011 Freescale Semiconductor, Inc.
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/init.h>
|
|
#include <linux/clk.h>
|
|
#include <linux/module.h>
|
|
#include <linux/device.h>
|
|
#include <linux/io.h>
|
|
#include <linux/spi/mxs-spi.h>
|
|
|
|
void mxs_ssp_set_clk_rate(struct mxs_ssp *ssp, unsigned int rate)
|
|
{
|
|
unsigned int ssp_clk, ssp_sck;
|
|
u32 clock_divide, clock_rate;
|
|
u32 val;
|
|
|
|
ssp_clk = clk_get_rate(ssp->clk);
|
|
|
|
for (clock_divide = 2; clock_divide <= 254; clock_divide += 2) {
|
|
clock_rate = DIV_ROUND_UP(ssp_clk, rate * clock_divide);
|
|
clock_rate = (clock_rate > 0) ? clock_rate - 1 : 0;
|
|
if (clock_rate <= 255)
|
|
break;
|
|
}
|
|
|
|
if (clock_divide > 254) {
|
|
dev_err(ssp->dev,
|
|
"%s: cannot set clock to %d\n", __func__, rate);
|
|
return;
|
|
}
|
|
|
|
ssp_sck = ssp_clk / clock_divide / (1 + clock_rate);
|
|
|
|
val = readl(ssp->base + HW_SSP_TIMING(ssp));
|
|
val &= ~(BM_SSP_TIMING_CLOCK_DIVIDE | BM_SSP_TIMING_CLOCK_RATE);
|
|
val |= BF_SSP(clock_divide, TIMING_CLOCK_DIVIDE);
|
|
val |= BF_SSP(clock_rate, TIMING_CLOCK_RATE);
|
|
writel(val, ssp->base + HW_SSP_TIMING(ssp));
|
|
|
|
ssp->clk_rate = ssp_sck;
|
|
|
|
dev_dbg(ssp->dev,
|
|
"%s: clock_divide %d, clock_rate %d, ssp_clk %d, rate_actual %d, rate_requested %d\n",
|
|
__func__, clock_divide, clock_rate, ssp_clk, ssp_sck, rate);
|
|
}
|
|
EXPORT_SYMBOL_GPL(mxs_ssp_set_clk_rate);
|