[PATCH v2 16/21] ARM: tegra: Add external memory controller driver

Colin Cross
2011-02-19T22:26:41Z

Signed-off-by: Colin Cross <ccross@android.com>
---
arch/arm/mach-tegra/Kconfig | 4 +
arch/arm/mach-tegra/Makefile | 1 +
arch/arm/mach-tegra/tegra2_emc.c | 172 ++++++++++++++++++++++++++++++++++++++
arch/arm/mach-tegra/tegra2_emc.h | 27 ++++++
4 files changed, 204 insertions(+), 0 deletions(-)
create mode 100644 arch/arm/mach-tegra/tegra2_emc.c
create mode 100644 arch/arm/mach-tegra/tegra2_emc.h

diff --git a/arch/arm/mach-tegra/Kconfig b/arch/arm/mach-tegra/Kconfig
index 9f4fc6b..42d44c7 100644
--- a/arch/arm/mach-tegra/Kconfig
+++ b/arch/arm/mach-tegra/Kconfig
@@ -71,3 +71,7 @@ config TEGRA_SYSTEM_DMA
several Tegra device drivers

endif
+
+config TEGRA_EMC_SCALING_ENABLE
+ bool "Enable scaling the memory frequency"
+ default n
diff --git a/arch/arm/mach-tegra/Makefile b/arch/arm/mach-tegra/Makefile
index 23de060..3fe357b 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 0000000..bd4fa27
--- /dev/null
+++ b/arch/arm/mach-tegra/tegra2_emc.c
@@ -0,0 +1,172 @@
+/*
+ * Copyright (C) 2010 Google, Inc.
+ *
+ * Author:
+ * Colin Cross <ccross@google.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 0000000..3515e57
--- /dev/null
+++ b/arch/arm/mach-tegra/tegra2_emc.h
@@ -0,0 +1,27 @@
+/*
+ * Copyright (C) 2010 Google, Inc.
+ *
+ * Author:
+ * Colin Cross <ccross@google.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);
--
1.7.3.1