12cdd3d719
aemif_calc_rate() can return a negative error value, so all the variables that get tested for this value need to be signed. The maximum bit width of WSETUP(WSETUP_MAX) appears to be 30 bits (0xf << 26). Using a signed instead of an unsigned integer shouldn't make a difference here. Signed-off-by: Nicolas Kaiser <nikai@nikai.net> Acked-by: Sekhar Nori <nsekhar@ti.com> Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
133 lines
3.7 KiB
C
133 lines
3.7 KiB
C
/*
|
|
* AEMIF support for DaVinci SoCs
|
|
*
|
|
* Copyright (C) 2010 Texas Instruments Incorporated. http://www.ti.com/
|
|
*
|
|
* This program is free software; you can redistribute it and/or modify
|
|
* it under the terms of the GNU General Public License version 2 as
|
|
* published by the Free Software Foundation.
|
|
*/
|
|
|
|
#include <linux/kernel.h>
|
|
#include <linux/io.h>
|
|
#include <linux/err.h>
|
|
#include <linux/clk.h>
|
|
#include <linux/module.h>
|
|
#include <linux/time.h>
|
|
|
|
#include <mach/aemif.h>
|
|
|
|
/* Timing value configuration */
|
|
|
|
#define TA(x) ((x) << 2)
|
|
#define RHOLD(x) ((x) << 4)
|
|
#define RSTROBE(x) ((x) << 7)
|
|
#define RSETUP(x) ((x) << 13)
|
|
#define WHOLD(x) ((x) << 17)
|
|
#define WSTROBE(x) ((x) << 20)
|
|
#define WSETUP(x) ((x) << 26)
|
|
|
|
#define TA_MAX 0x3
|
|
#define RHOLD_MAX 0x7
|
|
#define RSTROBE_MAX 0x3f
|
|
#define RSETUP_MAX 0xf
|
|
#define WHOLD_MAX 0x7
|
|
#define WSTROBE_MAX 0x3f
|
|
#define WSETUP_MAX 0xf
|
|
|
|
#define TIMING_MASK (TA(TA_MAX) | \
|
|
RHOLD(RHOLD_MAX) | \
|
|
RSTROBE(RSTROBE_MAX) | \
|
|
RSETUP(RSETUP_MAX) | \
|
|
WHOLD(WHOLD_MAX) | \
|
|
WSTROBE(WSTROBE_MAX) | \
|
|
WSETUP(WSETUP_MAX))
|
|
|
|
/*
|
|
* aemif_calc_rate - calculate timing data.
|
|
* @wanted: The cycle time needed in nanoseconds.
|
|
* @clk: The input clock rate in kHz.
|
|
* @max: The maximum divider value that can be programmed.
|
|
*
|
|
* On success, returns the calculated timing value minus 1 for easy
|
|
* programming into AEMIF timing registers, else negative errno.
|
|
*/
|
|
static int aemif_calc_rate(int wanted, unsigned long clk, int max)
|
|
{
|
|
int result;
|
|
|
|
result = DIV_ROUND_UP((wanted * clk), NSEC_PER_MSEC) - 1;
|
|
|
|
pr_debug("%s: result %d from %ld, %d\n", __func__, result, clk, wanted);
|
|
|
|
/* It is generally OK to have a more relaxed timing than requested... */
|
|
if (result < 0)
|
|
result = 0;
|
|
|
|
/* ... But configuring tighter timings is not an option. */
|
|
else if (result > max)
|
|
result = -EINVAL;
|
|
|
|
return result;
|
|
}
|
|
|
|
/**
|
|
* davinci_aemif_setup_timing - setup timing values for a given AEMIF interface
|
|
* @t: timing values to be progammed
|
|
* @base: The virtual base address of the AEMIF interface
|
|
* @cs: chip-select to program the timing values for
|
|
*
|
|
* This function programs the given timing values (in real clock) into the
|
|
* AEMIF registers taking the AEMIF clock into account.
|
|
*
|
|
* This function does not use any locking while programming the AEMIF
|
|
* because it is expected that there is only one user of a given
|
|
* chip-select.
|
|
*
|
|
* Returns 0 on success, else negative errno.
|
|
*/
|
|
int davinci_aemif_setup_timing(struct davinci_aemif_timing *t,
|
|
void __iomem *base, unsigned cs)
|
|
{
|
|
unsigned set, val;
|
|
int ta, rhold, rstrobe, rsetup, whold, wstrobe, wsetup;
|
|
unsigned offset = A1CR_OFFSET + cs * 4;
|
|
struct clk *aemif_clk;
|
|
unsigned long clkrate;
|
|
|
|
if (!t)
|
|
return 0; /* Nothing to do */
|
|
|
|
aemif_clk = clk_get(NULL, "aemif");
|
|
if (IS_ERR(aemif_clk))
|
|
return PTR_ERR(aemif_clk);
|
|
|
|
clkrate = clk_get_rate(aemif_clk);
|
|
|
|
clkrate /= 1000; /* turn clock into kHz for ease of use */
|
|
|
|
ta = aemif_calc_rate(t->ta, clkrate, TA_MAX);
|
|
rhold = aemif_calc_rate(t->rhold, clkrate, RHOLD_MAX);
|
|
rstrobe = aemif_calc_rate(t->rstrobe, clkrate, RSTROBE_MAX);
|
|
rsetup = aemif_calc_rate(t->rsetup, clkrate, RSETUP_MAX);
|
|
whold = aemif_calc_rate(t->whold, clkrate, WHOLD_MAX);
|
|
wstrobe = aemif_calc_rate(t->wstrobe, clkrate, WSTROBE_MAX);
|
|
wsetup = aemif_calc_rate(t->wsetup, clkrate, WSETUP_MAX);
|
|
|
|
if (ta < 0 || rhold < 0 || rstrobe < 0 || rsetup < 0 ||
|
|
whold < 0 || wstrobe < 0 || wsetup < 0) {
|
|
pr_err("%s: cannot get suitable timings\n", __func__);
|
|
return -EINVAL;
|
|
}
|
|
|
|
set = TA(ta) | RHOLD(rhold) | RSTROBE(rstrobe) | RSETUP(rsetup) |
|
|
WHOLD(whold) | WSTROBE(wstrobe) | WSETUP(wsetup);
|
|
|
|
val = __raw_readl(base + offset);
|
|
val &= ~TIMING_MASK;
|
|
val |= set;
|
|
__raw_writel(val, base + offset);
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(davinci_aemif_setup_timing);
|