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Subject[RFC PATCH 4/8] misc: emif: add basic infrastructure for EMIF driver
Date
EMIF is an SDRAM controller used in various Texas Instruments
SoCs. EMIF supports, based on its revision, one or more of
LPDDR2/DDR2/DDR3 protocols.

Add the basic infrastructure for EMIF driver that includes
driver registration, probe, parsing of platform data etc.

Signed-off-by: Aneesh V <aneesh@ti.com>
---
drivers/misc/Kconfig | 12 ++
drivers/misc/Makefile | 1 +
drivers/misc/emif.c | 300 +++++++++++++++++++++++++++++++++++++++++++++++++
include/linux/emif.h | 160 ++++++++++++++++++++++++++
4 files changed, 473 insertions(+), 0 deletions(-)
create mode 100644 drivers/misc/emif.c
create mode 100644 include/linux/emif.h
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index 8337bf6..d68184a 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -459,6 +459,18 @@ config DDR
information. This data is useful for drivers handling
DDR SDRAM controllers.

+config EMIF
+ tristate "Texas Instruments EMIF driver"
+ select DDR
+ help
+ This driver is for the EMIF module available in Texas Instruments
+ SoCs. EMIF is an SDRAM controller that, based on its revision,
+ supports one or more of DDR2, DDR3, and LPDDR2 SDRAM protocols.
+ This driver takes care of only LPDDR2 memories presently. The
+ functions of the driver includes re-configuring AC timing
+ parameters and other settings during frequency, voltage and
+ temperature changes
+
config ARM_CHARLCD
bool "ARM Ltd. Character LCD Driver"
depends on PLAT_VERSATILE
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 4759166..076db0f 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -37,6 +37,7 @@ obj-$(CONFIG_C2PORT) += c2port/
obj-$(CONFIG_IWMC3200TOP) += iwmc3200top/
obj-$(CONFIG_HMC6352) += hmc6352.o
obj-$(CONFIG_DDR) += jedec_ddr_data.o
+obj-$(CONFIG_EMIF) += emif.o
obj-y += eeprom/
obj-y += cb710/
obj-$(CONFIG_SPEAR13XX_PCIE_GADGET) += spear13xx_pcie_gadget.o
diff --git a/drivers/misc/emif.c b/drivers/misc/emif.c
new file mode 100644
index 0000000..ba1e3f9
--- /dev/null
+++ b/drivers/misc/emif.c
@@ -0,0 +1,300 @@
+/*
+ * EMIF driver
+ *
+ * Copyright (C) 2010 Texas Instruments, Inc.
+ *
+ * Aneesh V <aneesh@ti.com>
+ * Santosh Shilimkar <santosh.shilimkar@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/reboot.h>
+#include <linux/emif.h>
+#include <linux/io.h>
+#include <linux/device.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+#include <linux/seq_file.h>
+#include <linux/module.h>
+#include <linux/spinlock.h>
+#include "emif_regs.h"
+
+/**
+ * struct emif_data - Per device static data for driver's use
+ * @duplicate: Whether the DDR devices attached to this EMIF
+ * instance are exactly same as that on EMIF1. In
+ * this case we can save some memory and processing
+ * @temperature_level: Maximum temperature of LPDDR2 devices attached
+ * to this EMIF - read from MR4 register. If there
+ * are two devices attached to this EMIF, this
+ * value is the maximum of the two temperature
+ * levels.
+ * @irq: IRQ number
+ * @lock: lock for protecting temperature_level and
+ * associated actions from race conditions
+ * @base: base address of memory-mapped IO registers.
+ * @dev: device pointer.
+ * @addressing table with addressing information from the spec
+ * @regs_cache: An array of 'struct emif_regs' that stores
+ * calculated register values for different
+ * frequencies, to avoid re-calculating them on
+ * each DVFS transition.
+ * @curr_regs: The set of register values used in the last
+ * frequency change (i.e. corresponding to the
+ * frequency in effect at the moment)
+ * @plat_data: Pointer to saved platform data.
+ */
+struct emif_data {
+ u8 duplicate;
+ u8 temperature_level;
+ u32 irq;
+ spinlock_t lock; /* lock to prevent races */
+ void __iomem *base;
+ struct device *dev;
+ const struct lpddr2_addressing *addressing;
+ struct emif_regs *regs_cache[EMIF_MAX_NUM_FREQUENCIES];
+ struct emif_regs *curr_regs;
+ struct emif_platform_data *plat_data;
+};
+
+static struct emif_data *emif1;
+
+static void __exit cleanup_emif(struct emif_data *emif)
+{
+ if (emif) {
+ if (emif->plat_data) {
+ kfree(emif->plat_data->custom_configs);
+ kfree(emif->plat_data->timings);
+ kfree(emif->plat_data->min_tck);
+ kfree(emif->plat_data->device_info);
+ kfree(emif->plat_data);
+ }
+ kfree(emif);
+ }
+}
+
+static void get_default_timings(struct emif_data *emif)
+{
+ struct emif_platform_data *pd = emif->plat_data;
+
+ pd->timings = lpddr2_jedec_timings;
+ pd->timings_arr_size = ARRAY_SIZE(lpddr2_jedec_timings);
+
+ dev_warn(emif->dev, "Using default timings\n");
+}
+
+static int is_dev_data_valid(u32 type, u32 density, u32 io_width, u32 phy_type,
+ u32 ip_rev, struct device *dev)
+{
+ int valid;
+
+ valid = (type == DDR_TYPE_LPDDR2_S4 ||
+ type == DDR_TYPE_LPDDR2_S2)
+ && (density >= DDR_DENSITY_64Mb
+ && density <= DDR_DENSITY_8Gb)
+ && (io_width >= DDR_IO_WIDTH_8
+ && io_width <= DDR_IO_WIDTH_32);
+
+ /* Combinations of EMIF and PHY revisions that we support today */
+ switch (ip_rev) {
+ case EMIF_4D:
+ valid = valid && (phy_type == EMIF_PHY_TYPE_ATTILAPHY);
+ break;
+ case EMIF_4D5:
+ valid = valid && (phy_type == EMIF_PHY_TYPE_INTELLIPHY);
+ break;
+ default:
+ valid = 0;
+ }
+
+ if (!valid)
+ dev_err(dev, "Invalid DDR details\n");
+ return valid;
+}
+
+static int is_custom_config_valid(struct emif_custom_configs *cust_cfgs,
+ struct device *dev)
+{
+ int valid = 1;
+
+ if ((cust_cfgs->mask & EMIF_CUSTOM_CONFIG_LPMODE) &&
+ (cust_cfgs->lpmode != EMIF_LP_MODE_DISABLE))
+ valid = cust_cfgs->lpmode_freq_threshold &&
+ cust_cfgs->lpmode_timeout_performance &&
+ cust_cfgs->lpmode_timeout_power;
+
+ if (cust_cfgs->mask & EMIF_CUSTOM_CONFIG_TEMP_ALERT_POLL_INTERVAL)
+ valid = valid && cust_cfgs->temp_alert_poll_interval_ms;
+
+ if (!valid)
+ dev_warn(dev, "Invalid custom configs\n");
+
+ return valid;
+}
+
+static struct emif_data * __init get_device_details(
+ struct platform_device *pdev)
+{
+ u32 size;
+ struct emif_data *emif = NULL;
+ struct ddr_device_info *dev_info;
+ struct emif_platform_data *pd;
+
+ pd = pdev->dev.platform_data;
+
+ if (!(pd && pd->device_info && is_dev_data_valid(pd->device_info->type,
+ pd->device_info->density, pd->device_info->io_width,
+ pd->phy_type, pd->ip_rev, &pdev->dev)))
+ goto error;
+
+ emif = kzalloc(sizeof(struct emif_data), GFP_KERNEL);
+ pd = kmemdup(pd, sizeof(*pd), GFP_KERNEL);
+ dev_info = kmemdup(pd->device_info,
+ sizeof(*pd->device_info), GFP_KERNEL);
+
+ if (!emif || !pd || !dev_info)
+ goto error;
+
+ emif->plat_data = pd;
+ emif->dev = &pdev->dev;
+ emif->temperature_level = SDRAM_TEMP_NOMINAL;
+
+ pd->device_info = dev_info;
+
+ /*
+ * For EMIF instances other than EMIF1 see if the devices connected
+ * are exactly same as on EMIF1(which is typically the case). If so,
+ * mark it as a duplicate of EMIF1 and skip copying timings data.
+ * This will save some memory and some computation later.
+ */
+ emif->duplicate = emif1 && (memcmp(dev_info,
+ emif1->plat_data->device_info,
+ sizeof(struct ddr_device_info)) == 0);
+
+ if (emif->duplicate) {
+ pd->timings = NULL;
+ pd->min_tck = NULL;
+ goto out;
+ }
+
+ /*
+ * Copy custom configs - ignore allocation error, if any, as
+ * custom_configs is not very critical
+ */
+ if (pd->custom_configs)
+ pd->custom_configs = kmemdup(pd->custom_configs,
+ sizeof(*pd->custom_configs), GFP_KERNEL);
+
+ if (pd->custom_configs &&
+ !is_custom_config_valid(pd->custom_configs, emif->dev)) {
+ kfree(pd->custom_configs);
+ pd->custom_configs = NULL;
+ }
+
+ /*
+ * Copy timings and min-tck values from platform data. If it is not
+ * available or if memory allocation fails, use JEDEC defaults
+ */
+ size = sizeof(struct lpddr2_timings) * pd->timings_arr_size;
+ if (pd->timings)
+ pd->timings = kmemdup(pd->timings, size, GFP_KERNEL);
+
+ if (!pd->timings)
+ get_default_timings(emif);
+
+ if (pd->min_tck)
+ pd->min_tck = kmemdup(pd->min_tck, sizeof(*pd->min_tck),
+ GFP_KERNEL);
+
+ if (!pd->min_tck) {
+ pd->min_tck = &lpddr2_min_tck;
+ dev_warn(emif->dev, "Using default min-tck values\n");
+ }
+
+ goto out;
+
+error:
+ dev_err(&pdev->dev, "get_device_details() failure!!\n");
+ cleanup_emif(emif);
+ return NULL;
+
+out:
+ return emif;
+}
+
+static int __init emif_probe(struct platform_device *pdev)
+{
+ struct emif_data *emif;
+ struct resource *res;
+
+ emif = get_device_details(pdev);
+
+ if (!emif)
+ goto error;
+
+ if (!emif1)
+ emif1 = emif;
+
+ /* Save pointers to each other in emif and device structures */
+ emif->dev = &pdev->dev;
+ platform_set_drvdata(pdev, emif);
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!res)
+ goto error;
+
+ emif->base = ioremap(res->start, SZ_1M);
+ if (!emif->base)
+ goto error;
+
+ res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+ if (!res)
+ goto error;
+ emif->irq = res->start;
+
+ dev_info(&pdev->dev, "Device configured with addr = %p and IRQ%d\n",
+ emif->base, emif->irq);
+ return 0;
+
+error:
+ dev_err(&pdev->dev, "probe failure!!\n");
+ cleanup_emif(emif);
+ return -ENODEV;
+}
+
+static int __exit emif_remove(struct platform_device *pdev)
+{
+ struct emif_data *emif = platform_get_drvdata(pdev);
+
+ cleanup_emif(emif);
+
+ return 0;
+}
+
+static struct platform_driver emif_driver = {
+ .remove = __exit_p(emif_remove),
+ .driver = {
+ .name = "emif",
+ },
+};
+
+static int __init emif_register(void)
+{
+ return platform_driver_probe(&emif_driver, emif_probe);
+}
+
+static void __exit emif_unregister(void)
+{
+ platform_driver_unregister(&emif_driver);
+}
+
+module_init(emif_register);
+module_exit(emif_unregister);
+MODULE_DESCRIPTION("TI EMIF SDRAM Controller Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:emif");
+MODULE_AUTHOR("Texas Instruments Inc");
diff --git a/include/linux/emif.h b/include/linux/emif.h
new file mode 100644
index 0000000..4ddf20b
--- /dev/null
+++ b/include/linux/emif.h
@@ -0,0 +1,160 @@
+/*
+ * Definitions for EMIF SDRAM controller in TI SoCs
+ *
+ * Copyright (C) 2010 Texas Instruments, Inc.
+ *
+ * Aneesh V <aneesh@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.
+ */
+#ifndef __LINUX_EMIF_H
+#define __LINUX_EMIF_H
+
+#ifndef __ASSEMBLY__
+#include <linux/jedec_ddr.h>
+
+/*
+ * Maximum number of different frequencies supported by EMIF driver
+ * Determines the number of entries in the pointer array for register
+ * cache
+ */
+#define EMIF_MAX_NUM_FREQUENCIES 6
+
+/* EMIF_PWR_MGMT_CTRL register */
+/* Low power modes */
+#define EMIF_LP_MODE_DISABLE 0
+#define EMIF_LP_MODE_CLOCK_STOP 1
+#define EMIF_LP_MODE_SELF_REFRESH 2
+#define EMIF_LP_MODE_PWR_DN 4
+
+/* Hardware capabilities */
+#define EMIF_HW_CAPS_LL_INTERFACE 0x00000001
+
+/* EMIF IP Revisions */
+#define EMIF_4D 1
+#define EMIF_4D5 2
+
+/* PHY types */
+#define EMIF_PHY_TYPE_ATTILAPHY 1
+#define EMIF_PHY_TYPE_INTELLIPHY 2
+
+/* Custom config requests */
+#define EMIF_CUSTOM_CONFIG_LPMODE 0x00000001
+#define EMIF_CUSTOM_CONFIG_TEMP_ALERT_POLL_INTERVAL 0x00000002
+
+/*
+ * Structure containing shadow of important registers in EMIF
+ * The calculation function fills in this structure to be later used for
+ * initialisation and DVFS
+ */
+struct emif_regs {
+ u32 freq;
+ u32 ref_ctrl_shdw;
+ u32 ref_ctrl_shdw_derated;
+ u32 sdram_tim1_shdw;
+ u32 sdram_tim1_shdw_derated;
+ u32 sdram_tim2_shdw;
+ u32 sdram_tim3_shdw;
+ u32 sdram_tim3_shdw_derated;
+ u32 pwr_mgmt_ctrl_shdw;
+ union {
+ u32 read_idle_ctrl_shdw_normal;
+ u32 dll_calib_ctrl_shdw_normal;
+ };
+ union {
+ u32 read_idle_ctrl_shdw_volt_ramp;
+ u32 dll_calib_ctrl_shdw_volt_ramp;
+ };
+
+ u32 phy_ctrl_1_shdw;
+ u32 ext_phy_ctrl_2_shdw;
+ u32 ext_phy_ctrl_3_shdw;
+ u32 ext_phy_ctrl_4_shdw;
+};
+
+/**
+ * struct ddr_device_info - All information about the DDR device except AC
+ * timing parameters
+ * @type: Device type (LPDDR2-S4, LPDDR2-S2 etc)
+ * @density: Device density
+ * @io_width: Bus width
+ * @cs1_used: Whether there is a DDR device attached to the second
+ * chip-select(CS1) of this EMIF instance
+ * @cal_resistors_per_cs: Whether there is one calibration resistor per
+ * chip-select or whether it's a single one for both
+ * @manufacturer: Manufacturer name string
+ */
+struct ddr_device_info {
+ u32 type;
+ u32 density;
+ u32 io_width;
+ u32 cs1_used;
+ u32 cal_resistors_per_cs;
+ char manufacturer[10];
+};
+
+/**
+ * struct emif_custom_configs - Custom configuration parameters/policies
+ * passed from the platform layer
+ * @mask: Mask to indicate which configs are requested
+ * @lpmode: LPMODE to be used in PWR_MGMT_CTRL register
+ * @lpmode_timeout_performance: Timeout before LPMODE entry when higher
+ * performance is desired at the cost of power (typically
+ * at higher OPPs)
+ * @lpmode_timeout_power: Timeout before LPMODE entry when better power
+ * savings is desired and performance is not important
+ * (typically at lower loads indicated by lower OPPs)
+ * @lpmode_freq_threshold: The DDR frequency threshold to identify between
+ * the above two cases:
+ * timeout = (freq >= lpmode_freq_threshold) ?
+ * lpmode_timeout_performance :
+ * lpmode_timeout_power;
+ * @temp_alert_poll_interval_ms: LPDDR2 MR4 polling interval at nominal
+ * temperature(in milliseconds). When temperature is high
+ * polling is done 4 times as frequently.
+ */
+struct emif_custom_configs {
+ u32 mask;
+ u32 lpmode;
+ u32 lpmode_timeout_performance;
+ u32 lpmode_timeout_power;
+ u32 lpmode_freq_threshold;
+ u32 temp_alert_poll_interval_ms;
+};
+
+/**
+ * struct emif_platform_data - Platform data passed on EMIF platform
+ * device creation. Used by the driver.
+ * @hw_caps: Hw capabilities of the EMIF IP in the respective SoC
+ * @device_info: Device info structure containing information such
+ * as type, bus width, density etc
+ * @timings: Timings information from device datasheet passed
+ * as an array of 'struct lpddr2_timings'. Can be NULL
+ * if if default timings are ok
+ * @timings_arr_size: Size of the timings array. Depends on the number
+ * of different frequencies for which timings data
+ * is provided
+ * @min_tck: Minimum value of some timing parameters in terms
+ * of number of cycles. Can be NULL if default values
+ * are ok
+ * @custom_configs: Custom configurations requested by SoC or board
+ * code and the data for them. Can be NULL if default
+ * configurations done by the driver are ok. See
+ * documentation for 'struct emif_custom_configs' for
+ * more details
+ */
+struct emif_platform_data {
+ u32 hw_caps;
+ struct ddr_device_info *device_info;
+ const struct lpddr2_timings *timings;
+ u32 timings_arr_size;
+ const struct lpddr2_min_tck *min_tck;
+ struct emif_custom_configs *custom_configs;
+ u32 ip_rev;
+ u32 phy_type;
+};
+#endif /* __ASSEMBLY__ */
+
+#endif /* __LINUX_EMIF_H */
--
1.7.1


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