Permalink
Browse files

memory: emif: add basic infrastructure for EMIF driver

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>
Reviewed-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Reviewed-by: Benoit Cousson <b-cousson@ti.com>
[santosh.shilimkar@ti.com: Moved to drivers/memory from drivers/misc]
Signed-off-by: Santosh Shilimkar <santosh.shilimkar@ti.com>
Tested-by: Lokesh Vutla <lokeshvutla@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
  • Loading branch information...
1 parent 6c8b090 commit 7ec944538dde3d7f490bd4d2619051789db5c3c3 @aneeshv aneeshv committed with gregkh Apr 27, 2012
@@ -0,0 +1,57 @@
+TI EMIF SDRAM Controller Driver:
+
+Author
+========
+Aneesh V <aneesh@ti.com>
+
+Location
+============
+driver/memory/emif.c
+
+Supported SoCs:
+===================
+TI OMAP44xx
+TI OMAP54xx
+
+Menuconfig option:
+==========================
+Device Drivers
+ Memory devices
+ Texas Instruments EMIF driver
+
+Description
+===========
+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
+
+Platform Data (see include/linux/platform_data/emif_plat.h):
+=====================================================================
+DDR device details and other board dependent and SoC dependent
+information can be passed through platform data (struct emif_platform_data)
+- DDR device details: 'struct ddr_device_info'
+- Device AC timings: 'struct lpddr2_timings' and 'struct lpddr2_min_tck'
+- Custom configurations: customizable policy options through
+ 'struct emif_custom_configs'
+- IP revision
+- PHY type
+
+Interface to the external world:
+================================
+EMIF driver registers notifiers for voltage and frequency changes
+affecting EMIF and takes appropriate actions when these are invoked.
+- freq_pre_notify_handling()
+- freq_post_notify_handling()
+- volt_notify_handling()
+
+Debugfs
+========
+The driver creates two debugfs entries per device.
+- regcache_dump : dump of register values calculated and saved for all
+ frequencies used so far.
+- mr4 : last polled value of MR4 register in the LPDDR2 device. MR4
+ indicates the current temperature level of the device.
View
@@ -142,4 +142,6 @@ source "drivers/devfreq/Kconfig"
source "drivers/extcon/Kconfig"
+source "drivers/memory/Kconfig"
+
endmenu
View
@@ -135,3 +135,4 @@ obj-$(CONFIG_HYPERV) += hv/
obj-$(CONFIG_PM_DEVFREQ) += devfreq/
obj-$(CONFIG_EXTCON) += extcon/
+obj-$(CONFIG_MEMORY) += memory/
@@ -0,0 +1,22 @@
+#
+# Memory devices
+#
+
+menuconfig MEMORY
+ bool "Memory Controller drivers"
+
+if MEMORY
+
+config TI_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
+
+endif
@@ -0,0 +1,5 @@
+#
+# Makefile for memory devices
+#
+
+obj-$(CONFIG_TI_EMIF) += emif.o
View
@@ -0,0 +1,289 @@
+/*
+ * EMIF driver
+ *
+ * Copyright (C) 2012 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/platform_data/emif_plat.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/list.h>
+#include <memory/jedec_ddr.h>
+#include "emif.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.
+ * @node: node in the device list
+ * @base: base address of memory-mapped IO registers.
+ * @dev: device pointer.
+ * @plat_data: Pointer to saved platform data.
+ */
+struct emif_data {
+ u8 duplicate;
+ u8 temperature_level;
+ struct list_head node;
+ void __iomem *base;
+ struct device *dev;
+ struct emif_platform_data *plat_data;
+};
+
+static struct emif_data *emif1;
+static LIST_HEAD(device_list);
+
+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, "%s: using default timings\n", __func__);
+}
+
+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, "%s: invalid DDR details\n", __func__);
+ 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, "%s: invalid custom configs\n", __func__);
+
+ return valid;
+}
+
+static struct emif_data *__init_or_module get_device_details(
+ struct platform_device *pdev)
+{
+ u32 size;
+ struct emif_data *emif = NULL;
+ struct ddr_device_info *dev_info;
+ struct emif_custom_configs *cust_cfgs;
+ struct emif_platform_data *pd;
+ struct device *dev;
+ void *temp;
+
+ pd = pdev->dev.platform_data;
+ dev = &pdev->dev;
+
+ 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, dev))) {
+ dev_err(dev, "%s: invalid device data\n", __func__);
+ goto error;
+ }
+
+ emif = devm_kzalloc(dev, sizeof(*emif), GFP_KERNEL);
+ temp = devm_kzalloc(dev, sizeof(*pd), GFP_KERNEL);
+ dev_info = devm_kzalloc(dev, sizeof(*dev_info), GFP_KERNEL);
+
+ if (!emif || !pd || !dev_info) {
+ dev_err(dev, "%s:%d: allocation error\n", __func__, __LINE__);
+ goto error;
+ }
+
+ memcpy(temp, pd, sizeof(*pd));
+ pd = temp;
+ memcpy(dev_info, pd->device_info, sizeof(*dev_info));
+
+ pd->device_info = dev_info;
+ emif->plat_data = pd;
+ emif->dev = dev;
+ emif->temperature_level = SDRAM_TEMP_NOMINAL;
+
+ /*
+ * 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;
+ } else if (emif1) {
+ dev_warn(emif->dev, "%s: Non-symmetric DDR geometry\n",
+ __func__);
+ }
+
+ /*
+ * Copy custom configs - ignore allocation error, if any, as
+ * custom_configs is not very critical
+ */
+ cust_cfgs = pd->custom_configs;
+ if (cust_cfgs && is_custom_config_valid(cust_cfgs, dev)) {
+ temp = devm_kzalloc(dev, sizeof(*cust_cfgs), GFP_KERNEL);
+ if (temp)
+ memcpy(temp, cust_cfgs, sizeof(*cust_cfgs));
+ else
+ dev_warn(dev, "%s:%d: allocation error\n", __func__,
+ __LINE__);
+ pd->custom_configs = temp;
+ }
+
+ /*
+ * 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) {
+ temp = devm_kzalloc(dev, size, GFP_KERNEL);
+ if (temp) {
+ memcpy(temp, pd->timings, sizeof(*pd->timings));
+ pd->timings = temp;
+ } else {
+ dev_warn(dev, "%s:%d: allocation error\n", __func__,
+ __LINE__);
+ get_default_timings(emif);
+ }
+ } else {
+ get_default_timings(emif);
+ }
+
+ if (pd->min_tck) {
+ temp = devm_kzalloc(dev, sizeof(*pd->min_tck), GFP_KERNEL);
+ if (temp) {
+ memcpy(temp, pd->min_tck, sizeof(*pd->min_tck));
+ pd->min_tck = temp;
+ } else {
+ dev_warn(dev, "%s:%d: allocation error\n", __func__,
+ __LINE__);
+ pd->min_tck = &lpddr2_jedec_min_tck;
+ }
+ } else {
+ pd->min_tck = &lpddr2_jedec_min_tck;
+ }
+
+out:
+ return emif;
+
+error:
+ return NULL;
+}
+
+static int __init_or_module emif_probe(struct platform_device *pdev)
+{
+ struct emif_data *emif;
+ struct resource *res;
+
+ emif = get_device_details(pdev);
+ if (!emif) {
+ pr_err("%s: error getting device data\n", __func__);
+ goto error;
+ }
+
+ if (!emif1)
+ emif1 = emif;
+
+ list_add(&emif->node, &device_list);
+
+ /* 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) {
+ dev_err(emif->dev, "%s: error getting memory resource\n",
+ __func__);
+ goto error;
+ }
+
+ emif->base = devm_request_and_ioremap(emif->dev, res);
+ if (!emif->base) {
+ dev_err(emif->dev, "%s: devm_request_and_ioremap() failed\n",
+ __func__);
+ goto error;
+ }
+
+ dev_info(&pdev->dev, "%s: device configured with addr = %p\n",
+ __func__, emif->base);
+
+ return 0;
+error:
+ return -ENODEV;
+}
+
+static struct platform_driver emif_driver = {
+ .driver = {
+ .name = "emif",
+ },
+};
+
+static int __init_or_module 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");
Oops, something went wrong.

0 comments on commit 7ec9445

Please sign in to comment.