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    SubjectRe: [RFC PATCH 4/8] misc: emif: add basic infrastructure for EMIF driver
    On Saturday 04 February 2012 05:46 PM, Aneesh V wrote:
    > 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

    Add TI prefix here since it's TI IP and not a generic one.

    > + 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.
    Fix year. 2012
    > + *
    > + * 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);
    > + }
    > +}
    > +
    You might want to consider use of devm_kzalloc() kind of
    API so that you can get rid of above free stuff.

    > +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");
    > +}
    Would be good if you add __line__ in all the errors and
    warnings. Helps to trace messages faster.

    > +
    > +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;
    Generally return 0 means success. you might want to consider
    returning -EINVAL or similar.

    > +}
    > +
    > +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;
    > +}
    > +
    Ditto

    > +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;
    > +
    extra line
    > + 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);
    > +
    here too
    > + if (!emif || !pd || !dev_info)
    > + goto error;
    > +
    > + emif->plat_data = pd;
    > + emif->dev = &pdev->dev;
    > + emif->temperature_level = SDRAM_TEMP_NOMINAL;
    > +
    and here
    > + 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);
    > +
    and here
    > + 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) {
    else on above if should work, right ?

    > + 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);
    > +
    extra line

    > + 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;
    you might want add a line here
    > + emif->irq = res->start;
    > +
    And remove this one
    > + 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.
    > + *
    2012

    > + * 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 */
    Combine above two line comments in one
    comment.

    > +#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
    > +

    try to aling numbers for all the above defines.

    With above minor comments, the patch looks fine to me.

    Regards
    Santosh


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