tegra2_emc.c
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/*
* Copyright (C) 2011 Google, Inc.
*
* Author:
* Colin Cross <ccross@android.com>
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
*/
#include <linux/kernel.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/module.h>
#include <mach/iomap.h>
#include "tegra2_emc.h"
#ifdef CONFIG_TEGRA_EMC_SCALING_ENABLE
static bool emc_enable = true;
#else
static bool emc_enable;
#endif
module_param(emc_enable, bool, 0644);
static void __iomem *emc = IO_ADDRESS(TEGRA_EMC_BASE);
static const struct tegra_emc_table *tegra_emc_table;
static int tegra_emc_table_size;
static inline void emc_writel(u32 val, unsigned long addr)
{
writel(val, emc + addr);
}
static inline u32 emc_readl(unsigned long addr)
{
return readl(emc + addr);
}
static const unsigned long emc_reg_addr[TEGRA_EMC_NUM_REGS] = {
0x2c, /* RC */
0x30, /* RFC */
0x34, /* RAS */
0x38, /* RP */
0x3c, /* R2W */
0x40, /* W2R */
0x44, /* R2P */
0x48, /* W2P */
0x4c, /* RD_RCD */
0x50, /* WR_RCD */
0x54, /* RRD */
0x58, /* REXT */
0x5c, /* WDV */
0x60, /* QUSE */
0x64, /* QRST */
0x68, /* QSAFE */
0x6c, /* RDV */
0x70, /* REFRESH */
0x74, /* BURST_REFRESH_NUM */
0x78, /* PDEX2WR */
0x7c, /* PDEX2RD */
0x80, /* PCHG2PDEN */
0x84, /* ACT2PDEN */
0x88, /* AR2PDEN */
0x8c, /* RW2PDEN */
0x90, /* TXSR */
0x94, /* TCKE */
0x98, /* TFAW */
0x9c, /* TRPAB */
0xa0, /* TCLKSTABLE */
0xa4, /* TCLKSTOP */
0xa8, /* TREFBW */
0xac, /* QUSE_EXTRA */
0x114, /* FBIO_CFG6 */
0xb0, /* ODT_WRITE */
0xb4, /* ODT_READ */
0x104, /* FBIO_CFG5 */
0x2bc, /* CFG_DIG_DLL */
0x2c0, /* DLL_XFORM_DQS */
0x2c4, /* DLL_XFORM_QUSE */
0x2e0, /* ZCAL_REF_CNT */
0x2e4, /* ZCAL_WAIT_CNT */
0x2a8, /* AUTO_CAL_INTERVAL */
0x2d0, /* CFG_CLKTRIM_0 */
0x2d4, /* CFG_CLKTRIM_1 */
0x2d8, /* CFG_CLKTRIM_2 */
};
/* Select the closest EMC rate that is higher than the requested rate */
long tegra_emc_round_rate(unsigned long rate)
{
int i;
int best = -1;
unsigned long distance = ULONG_MAX;
if (!tegra_emc_table)
return -EINVAL;
if (!emc_enable)
return -EINVAL;
pr_debug("%s: %lu\n", __func__, rate);
/*
* The EMC clock rate is twice the bus rate, and the bus rate is
* measured in kHz
*/
rate = rate / 2 / 1000;
for (i = 0; i < tegra_emc_table_size; i++) {
if (tegra_emc_table[i].rate >= rate &&
(tegra_emc_table[i].rate - rate) < distance) {
distance = tegra_emc_table[i].rate - rate;
best = i;
}
}
if (best < 0)
return -EINVAL;
pr_debug("%s: using %lu\n", __func__, tegra_emc_table[best].rate);
return tegra_emc_table[best].rate * 2 * 1000;
}
/*
* The EMC registers have shadow registers. When the EMC clock is updated
* in the clock controller, the shadow registers are copied to the active
* registers, allowing glitchless memory bus frequency changes.
* This function updates the shadow registers for a new clock frequency,
* and relies on the clock lock on the emc clock to avoid races between
* multiple frequency changes
*/
int tegra_emc_set_rate(unsigned long rate)
{
int i;
int j;
if (!tegra_emc_table)
return -EINVAL;
/*
* The EMC clock rate is twice the bus rate, and the bus rate is
* measured in kHz
*/
rate = rate / 2 / 1000;
for (i = 0; i < tegra_emc_table_size; i++)
if (tegra_emc_table[i].rate == rate)
break;
if (i >= tegra_emc_table_size)
return -EINVAL;
pr_debug("%s: setting to %lu\n", __func__, rate);
for (j = 0; j < TEGRA_EMC_NUM_REGS; j++)
emc_writel(tegra_emc_table[i].regs[j], emc_reg_addr[j]);
emc_readl(tegra_emc_table[i].regs[TEGRA_EMC_NUM_REGS - 1]);
return 0;
}
void tegra_init_emc(const struct tegra_emc_table *table, int table_size)
{
tegra_emc_table = table;
tegra_emc_table_size = table_size;
}