Date:	Thu, 16 Feb 2012 16:45:25 +0530
From:	Aneesh V <aneesh@...com>
To:	Santosh Shilimkar <santosh.shilimkar@...com>
CC:	linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org,
	akpm@...ux-foundation.org
Subject: Re: [RFC PATCH 4/8] misc: emif: add basic infrastructure for EMIF
 driver

On Thursday 16 February 2012 04:03 PM, Santosh Shilimkar wrote:
> 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@...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.

Ok.

>
>> +	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@...com>
>> + * Santosh Shilimkar<santosh.shilimkar@...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.

I had considered that. But please note that most of these pointers are
initialized using kmemdup() and kmemdup() doesn't have a 'devm_'
equivalent. So, I didn't use it even for the regular kmalloc() cases in
order to have a uniform cleanup approach.

>
>> +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.

Ok. I shall add __FILE__ and __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, "Invalid DDR details\n");
>> +	return valid;
> Generally return 0 means success. you might want to consider
> returning -EINVAL or similar.

Please note that the function name here is a predicate. In this case 1
for success 0 for failure is correct, I believe.

>
>> +}
>> +
>> +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

Will fix them all.

>> +	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 ?

No. Please note that the pd->min_tck is allocated as part of the above
if.

>
>> +		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

will do.

>> +	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

Will fix.

>
>> + * Aneesh V<aneesh@...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.

Will do.

>
>> +#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.

Will do.

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

Thanks,
Aneesh
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