Re: [RFC PATCH 4/8] misc: emif: add basic infrastructure for EMIF driver

[Santosh Shilimkar <santosh.shilimkar@ti.com>]

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