diff options
Diffstat (limited to 'arch/arm/mach-tegra/tegra2_emc.c')
| -rw-r--r-- | arch/arm/mach-tegra/tegra2_emc.c | 178 |
1 files changed, 178 insertions, 0 deletions
diff --git a/arch/arm/mach-tegra/tegra2_emc.c b/arch/arm/mach-tegra/tegra2_emc.c new file mode 100644 index 000000000000..0f7ae6e90b55 --- /dev/null +++ b/arch/arm/mach-tegra/tegra2_emc.c @@ -0,0 +1,178 @@ +/* + * 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; +} |