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authorColin Cross <ccross@android.com>2011-02-12 18:22:49 -0800
committerColin Cross <ccross@android.com>2011-02-21 00:16:45 -0800
commitefdf72ad5c42b529286a1991f51badb030043719 (patch)
tree5ca9c1d934b989479ef4c4c5021feca3cb54f98d /arch/arm/mach-tegra
parent4db4afb4df93425708ca19417921bcc6a6306476 (diff)
ARM: tegra: Add external memory controller driver
The frequency memory bus on Tegra can be adjusted without disabling accesses to memory by updating the memory configuration registers from a per-board table, and then changing the clock frequency. The clock controller and memory controller have an interlock that prevents the new memory registers from taking effect until the clock frequency change. Acked-by: Olof Johansson <olof@lixom.net> Signed-off-by: Colin Cross <ccross@android.com>
Diffstat (limited to 'arch/arm/mach-tegra')
-rw-r--r--arch/arm/mach-tegra/Kconfig3
-rw-r--r--arch/arm/mach-tegra/Makefile1
-rw-r--r--arch/arm/mach-tegra/tegra2_emc.c178
-rw-r--r--arch/arm/mach-tegra/tegra2_emc.h27
4 files changed, 209 insertions, 0 deletions
diff --git a/arch/arm/mach-tegra/Kconfig b/arch/arm/mach-tegra/Kconfig
index f0fda77395e5..cac8a79e738e 100644
--- a/arch/arm/mach-tegra/Kconfig
+++ b/arch/arm/mach-tegra/Kconfig
@@ -65,3 +65,6 @@ config TEGRA_SYSTEM_DMA
several Tegra device drivers
endif
+
+config TEGRA_EMC_SCALING_ENABLE
+ bool "Enable scaling the memory frequency"
diff --git a/arch/arm/mach-tegra/Makefile b/arch/arm/mach-tegra/Makefile
index 23de0600a19d..3fe357bc763c 100644
--- a/arch/arm/mach-tegra/Makefile
+++ b/arch/arm/mach-tegra/Makefile
@@ -9,6 +9,7 @@ obj-y += powergate.o
obj-y += fuse.o
obj-$(CONFIG_ARCH_TEGRA_2x_SOC) += clock.o
obj-$(CONFIG_ARCH_TEGRA_2x_SOC) += tegra2_clocks.o
+obj-$(CONFIG_ARCH_TEGRA_2x_SOC) += tegra2_emc.o
obj-$(CONFIG_ARCH_TEGRA_2x_SOC) += pinmux-t2-tables.o
obj-$(CONFIG_SMP) += platsmp.o localtimer.o headsmp.o
obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o
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;
+}
diff --git a/arch/arm/mach-tegra/tegra2_emc.h b/arch/arm/mach-tegra/tegra2_emc.h
new file mode 100644
index 000000000000..19f08cb31603
--- /dev/null
+++ b/arch/arm/mach-tegra/tegra2_emc.h
@@ -0,0 +1,27 @@
+/*
+ * 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.
+ *
+ */
+
+#define TEGRA_EMC_NUM_REGS 46
+
+struct tegra_emc_table {
+ unsigned long rate;
+ u32 regs[TEGRA_EMC_NUM_REGS];
+};
+
+int tegra_emc_set_rate(unsigned long rate);
+long tegra_emc_round_rate(unsigned long rate);
+void tegra_init_emc(const struct tegra_emc_table *table, int table_size);