Subject: [PATCH 07/12] memory: davinci-aemif: introduce AEMIF driver

From: [email-masked] (ivan.khoronzhuk)
Date: Tue, 26 Nov 2013 19:44:55 +0200

On 11/26/2013 09:20 AM, Sekhar Nori wrote:
> On Monday 11 November 2013 10:36 PM, Khoronzhuk, Ivan wrote:
>> Add new AEMIF driver for EMIF16 davinci controller. The EMIF16 module
>> is intended to provide a glue-less interface to a variety of
>> asynchronous memory devices like ASRA M, NOR and NAND memory. A total
>> of 256M bytes of any of these memories can be accessed at any given
>> time via four chip selects with 64M byte access per chip select.
>>
>> Synchronous memories such as DDR1 SD RAM, SDR SDRAM and Mobile SDR
>> are not supported.
>>
>> See http://www.ti.com/lit/ug/sprugz3a/sprugz3a.pdf
>>
>> Signed-off-by: Ivan Khoronzhuk <[email-masked]>
>> ---
>>   drivers/memory/Kconfig         |   11 ++
>>   drivers/memory/Makefile        |    1 +
>>   drivers/memory/davinci-aemif.c |  415 ++++++++++++++++++++++++++++++++++++++++
>>   3 files changed, 427 insertions(+)
>>   create mode 100644 drivers/memory/davinci-aemif.c
>>
>> diff --git a/drivers/memory/Kconfig b/drivers/memory/Kconfig
>> index 29a11db..010e75e 100644
>> --- a/drivers/memory/Kconfig
>> +++ b/drivers/memory/Kconfig
>> @@ -7,6 +7,17 @@ menuconfig MEMORY
>>
>>   if MEMORY
>>
>> +config TI_DAVINCI_AEMIF
>> +       bool "Texas Instruments DaVinci AEMIF driver"
> 
> This driver cannot be a module? If not, why not?
> 

Yes it can be a module, I will correct it.

>> +       depends on (ARCH_DAVINCI || ARCH_KEYSTONE) && OF
>> +       help
>> +         This driver is for the AEMIF module available in Texas Instruments
>> +         SoCs. AEMIF stands for Asynchronous External Memory Interface and
>> +         is intended to provide a glue-less interface to a variety of
>> +         asynchronuous memory devices like ASRAM, NOR and NAND memory. A total
>> +         of 256M bytes of any of these memories can be accessed at a given
>> +         time via four chip selects with 64M byte access per chip select.
>> +
>>   config TI_EMIF
>>          tristate "Texas Instruments EMIF driver"
>>          depends on ARCH_OMAP2PLUS
>> diff --git a/drivers/memory/Makefile b/drivers/memory/Makefile
>> index 969d923..af14126 100644
>> --- a/drivers/memory/Makefile
>> +++ b/drivers/memory/Makefile
>> @@ -5,6 +5,7 @@
>>   ifeq ($(CONFIG_DDR),y)
>>   obj-$(CONFIG_OF)               += of_memory.o
>>   endif
>> +obj-$(CONFIG_TI_DAVINCI_AEMIF) += davinci-aemif.o
>>   obj-$(CONFIG_TI_EMIF)          += emif.o
>>   obj-$(CONFIG_MVEBU_DEVBUS)     += mvebu-devbus.o
>>   obj-$(CONFIG_TEGRA20_MC)       += tegra20-mc.o
>> diff --git a/drivers/memory/davinci-aemif.c b/drivers/memory/davinci-aemif.c
>> new file mode 100644
>> index 0000000..e36b74b
>> --- /dev/null
>> +++ b/drivers/memory/davinci-aemif.c
>> @@ -0,0 +1,415 @@
>> +/*
>> + * DaVinci/Keystone AEMIF driver
>> + *
>> + * Copyright (C) 2010 - 2013 Texas Instruments Incorporated. http://www.ti.com/
>> + * Copyright (C) Heiko Schocher <[email-masked]>
>> + * Copyright (C) Ivan Khoronzhuk <[email-masked]>
> 
> Just checking: You meant Author: ? Code is already copyrighted to TI by
> line above.
> 

It will be

Author:
Heiko Schocher <[email-masked]>
Ivan Khoronzhuk <[email-masked]>

>> + *
>> + * 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/clk.h>
>> +#include <linux/err.h>
>> +#include <linux/io.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/platform_device.h>
>> +
>> +#define TA_SHIFT       2
>> +#define RHOLD_SHIFT    4
>> +#define RSTROBE_SHIFT  7
>> +#define RSETUP_SHIFT   13
>> +#define WHOLD_SHIFT    17
>> +#define WSTROBE_SHIFT  20
>> +#define WSETUP_SHIFT   26
>> +#define EW_SHIFT       30
>> +#define SS_SHIFT       31
>> +
>> +#define TA(x)          ((x) << TA_SHIFT)
>> +#define RHOLD(x)       ((x) << RHOLD_SHIFT)
>> +#define RSTROBE(x)     ((x) << RSTROBE_SHIFT)
>> +#define RSETUP(x)      ((x) << RSETUP_SHIFT)
>> +#define WHOLD(x)       ((x) << WHOLD_SHIFT)
>> +#define WSTROBE(x)     ((x) << WSTROBE_SHIFT)
>> +#define WSETUP(x)      ((x) << WSETUP_SHIFT)
>> +#define EW(x)          ((x) << EW_SHIFT)
>> +#define SS(x)          ((x) << SS_SHIFT)
>> +
>> +#define ASIZE_MAX      0x1
>> +#define TA_MAX         0x3
>> +#define RHOLD_MAX      0x7
>> +#define RSTROBE_MAX    0x3f
>> +#define RSETUP_MAX     0xf
>> +#define WHOLD_MAX      0x7
>> +#define WSTROBE_MAX    0x3f
>> +#define WSETUP_MAX     0xf
>> +#define EW_MAX         0x1
>> +#define SS_MAX         0x1
>> +#define NUM_CS         4
>> +
>> +#define TA_VAL(x)      (((x) & TA(TA_MAX)) >> TA_SHIFT)
>> +#define RHOLD_VAL(x)   (((x) & RHOLD(RHOLD_MAX)) >> RHOLD_SHIFT)
>> +#define RSTROBE_VAL(x) (((x) & RSTROBE(RSTROBE_MAX)) >> RSTROBE_SHIFT)
>> +#define RSETUP_VAL(x)  (((x) & RSETUP(RSETUP_MAX)) >> RSETUP_SHIFT)
>> +#define WHOLD_VAL(x)   (((x) & WHOLD(WHOLD_MAX)) >> WHOLD_SHIFT)
>> +#define WSTROBE_VAL(x) (((x) & WSTROBE(WSTROBE_MAX)) >> WSTROBE_SHIFT)
>> +#define WSETUP_VAL(x)  (((x) & WSETUP(WSETUP_MAX)) >> WSETUP_SHIFT)
>> +#define EW_VAL(x)      (((x) & EW(EW_MAX)) >> EW_SHIFT)
>> +#define SS_VAL(x)      (((x) & SS(SS_MAX)) >> SS_SHIFT)
>> +
>> +#define NRCSR_OFFSET   0x00
>> +#define AWCCR_OFFSET   0x04
>> +#define A1CR_OFFSET    0x10
>> +
>> +#define ACR_ASIZE_MASK 0x3
>> +#define ACR_EW_MASK    BIT(30)
>> +#define ACR_SS_MASK    BIT(31)
>> +#define ASIZE_16BIT    1
>> +
>> +#define CONFIG_MASK    (TA(TA_MAX) | \
>> +                               RHOLD(RHOLD_MAX) | \
>> +                               RSTROBE(RSTROBE_MAX) |  \
>> +                               RSETUP(RSETUP_MAX) | \
>> +                               WHOLD(WHOLD_MAX) | \
>> +                               WSTROBE(WSTROBE_MAX) | \
>> +                               WSETUP(WSETUP_MAX) | \
>> +                               EW(EW_MAX) | SS(SS_MAX) | \
>> +                               ASIZE_MAX)
>> +
>> +#define DRV_NAME       "davinci-aemif"
>> +
>> +/**
>> + * structure to hold cs parameters
>> + * @cs: chip-select number
>> + * @wstrobe: write strobe width, ns
>> + * @rstrobe: read strobe width, ns
>> + * @wsetup: write setup width, ns
>> + * @whold: write hold width, ns
>> + * @rsetup: read setup width, ns
>> + * @rhold: read hold width, ns
>> + * @ta: minimum turn around time, ns
>> + * @enable_ss: enable/disable select strobe mode
>> + * @enable_ew: enable/disable extended wait mode
>> + * @asize: width of the asynchronous device's data bus
>> + */
>> +struct davinci_aemif_cs_data {
>> +       u8      cs;
>> +       u16     wstrobe;
>> +       u16     rstrobe;
>> +       u8      wsetup;
>> +       u8      whold;
>> +       u8      rsetup;
>> +       u8      rhold;
>> +       u8      ta;
>> +       u8      enable_ss;
>> +       u8      enable_ew;
>> +       u8      asize;
>> +};
>> +
>> +/**
>> + * structure to hold device data
>> + * @base: base address of AEMIF registers
>> + * @clk: source clock
>> + * @clk_rate: clock's rate in kHz
>> + * @num_cs: number of assigned chip-selects
>> + * @cs_data: array of chip-select settings
>> + */
>> +struct davinci_aemif_device {
>> +       struct device *dev;
>> +       void __iomem *base;
>> +       struct clk *clk;
>> +       unsigned long clk_rate;
>> +       u8 num_cs;
>> +       int cs_offset;
>> +       struct davinci_aemif_cs_data cs_data[NUM_CS];
>> +};
>> +
>> +static struct davinci_aemif_device *aemif;
>> +/**
>> + * davinci_aemif_calc_rate - calculate timing data.
>> + * @wanted: The cycle time needed in nanoseconds.
>> + * @clk: The input clock rate in kHz.
>> + * @max: The maximum divider value that can be programmed.
>> + *
>> + * On success, returns the calculated timing value minus 1 for easy
>> + * programming into AEMIF timing registers, else negative errno.
>> + */
>> +static int davinci_aemif_calc_rate(int wanted, unsigned long clk, int max)
>> +{
>> +       int result;
>> +
>> +       result = DIV_ROUND_UP((wanted * clk), NSEC_PER_MSEC) - 1;
>> +
>> +       dev_dbg(aemif->dev, "%s: result %d from %ld, %d\n", __func__, result,
>> +               clk, wanted);
>> +
>> +       /* It is generally OK to have a more relaxed timing than requested... */
>> +       if (result < 0)
>> +               result = 0;
>> +
>> +       /* ... But configuring tighter timings is not an option. */
>> +       else if (result > max)
>> +               result = -EINVAL;
>> +
>> +       return result;
>> +}
>> +
>> +/**
>> + * davinci_aemif_config_abus - configure async bus parameters
>> + * @data: aemif chip select configuration
>> + *
>> + * This function programs the given timing values (in real clock) into the
>> + * AEMIF registers taking the AEMIF clock into account.
>> + *
>> + * This function does not use any locking while programming the AEMIF
>> + * because it is expected that there is only one user of a given
>> + * chip-select.
>> + *
>> + * Returns 0 on success, else negative errno.
>> + */
>> +static int davinci_aemif_config_abus(struct davinci_aemif_cs_data *data)
>> +{
>> +       int ta, rhold, rstrobe, rsetup, whold, wstrobe, wsetup;
>> +       unsigned offset;
>> +       u32 set, val;
>> +
>> +       offset = A1CR_OFFSET + (data->cs - aemif->cs_offset) * 4;
>> +
>> +       ta      = davinci_aemif_calc_rate(data->ta, aemif->clk_rate, TA_MAX);
>> +       rhold   = davinci_aemif_calc_rate(data->rhold, aemif->clk_rate,
>> +                                         RHOLD_MAX);
>> +       rstrobe = davinci_aemif_calc_rate(data->rstrobe, aemif->clk_rate,
>> +                                         RSTROBE_MAX);
>> +       rsetup  = davinci_aemif_calc_rate(data->rsetup, aemif->clk_rate,
>> +                                         RSETUP_MAX);
>> +       whold   = davinci_aemif_calc_rate(data->whold, aemif->clk_rate,
>> +                                         WHOLD_MAX);
>> +       wstrobe = davinci_aemif_calc_rate(data->wstrobe, aemif->clk_rate,
>> +                                         WSTROBE_MAX);
>> +       wsetup  = davinci_aemif_calc_rate(data->wsetup, aemif->clk_rate,
>> +                                         WSETUP_MAX);
>> +
>> +       if (ta < 0 || rhold < 0 || rstrobe < 0 || rsetup < 0 ||
>> +                       whold < 0 || wstrobe < 0 || wsetup < 0) {
>> +               dev_err(aemif->dev, "%s: cannot get suitable timings\n",
>> +                       __func__);
>> +               return -EINVAL;
>> +       }
>> +
>> +       set = TA(ta) | RHOLD(rhold) | RSTROBE(rstrobe) | RSETUP(rsetup) |
>> +               WHOLD(whold) | WSTROBE(wstrobe) | WSETUP(wsetup);
>> +
>> +       set |= (data->asize & ACR_ASIZE_MASK);
>> +       if (data->enable_ew)
>> +               set |= ACR_EW_MASK;
>> +       if (data->enable_ss)
>> +               set |= ACR_SS_MASK;
>> +
>> +       val = readl(aemif->base + offset);
>> +       val &= ~CONFIG_MASK;
>> +       val |= set;
>> +       writel(val, aemif->base + offset);
>> +
>> +       return 0;
>> +}
>> +
>> +inline int davinci_aemif_cycles_to_nsec(int val)
>> +{
>> +       return ((val + 1) * NSEC_PER_MSEC) / aemif->clk_rate;
>> +}
>> +
>> +/**
>> + * davinci_aemif_get_hw_params - function to read hw register values
>> + * @data: ptr to cs data
>> + *
>> + * This function reads the defaults from the registers and update
>> + * the timing values. Required for get/set commands and also for
>> + * the case when driver needs to use defaults in hardware.
>> + */
>> +static void davinci_aemif_get_hw_params(struct davinci_aemif_cs_data *data)
>> +{
>> +       u32 val, offset;
>> +       offset = A1CR_OFFSET + (data->cs - aemif->cs_offset) * 4;
>> +
>> +       val = readl(aemif->base + offset);
>> +       data->ta = davinci_aemif_cycles_to_nsec(TA_VAL(val));
>> +       data->rhold = davinci_aemif_cycles_to_nsec(RHOLD_VAL(val));
>> +       data->rstrobe = davinci_aemif_cycles_to_nsec(RSTROBE_VAL(val));
>> +       data->rsetup = davinci_aemif_cycles_to_nsec(RSETUP_VAL(val));
>> +       data->whold = davinci_aemif_cycles_to_nsec(WHOLD_VAL(val));
>> +       data->wstrobe = davinci_aemif_cycles_to_nsec(WSTROBE_VAL(val));
>> +       data->wsetup = davinci_aemif_cycles_to_nsec(WSETUP_VAL(val));
>> +       data->enable_ew = EW_VAL(val);
>> +       data->enable_ss = SS_VAL(val);
>> +       data->asize = val & ASIZE_MAX;
>> +}
>> +
>> +/**
>> + * of_davinci_aemif_parse_abus_config - parse CS configuration from DT
>> + * @np: device node ptr
>> + *
>> + * This function update the emif async bus configuration based on the values
>> + * configured in a cs device binding node.
>> + */
>> +static int of_davinci_aemif_parse_abus_config(struct device_node *np)
>> +{
>> +       struct davinci_aemif_cs_data *data;
>> +       unsigned long cs;
>> +       u32 val;
>> +
>> +       if (kstrtoul(np->name + 2, 10, &cs) < 0) {
>> +               dev_dbg(aemif->dev, "cs name is incorrect");
>> +               return -EINVAL;
>> +       }
>> +
>> +       if (cs - aemif->cs_offset >= NUM_CS || cs < aemif->cs_offset) {
>> +               dev_dbg(aemif->dev, "cs number is incorrect %lu", cs);
>> +               return -EINVAL;
>> +       }
>> +
>> +       if (aemif->num_cs >= NUM_CS) {
>> +               dev_dbg(aemif->dev, "cs count is more than %d", NUM_CS);
>> +               return -EINVAL;
>> +       }
>> +
>> +       data = &aemif->cs_data[aemif->num_cs++];
>> +       data->cs = cs;
>> +
>> +       /* read the current value in the hw register */
>> +       davinci_aemif_get_hw_params(data);
>> +
>> +       /* override the values from device node */
>> +       of_property_read_u8(np, "ti,davinci-cs-ta", &data->ta);
>> +       of_property_read_u8(np, "ti,davinci-cs-rhold", &data->rhold);
>> +       of_property_read_u16(np, "ti,davinci-cs-rstrobe", &data->rstrobe);
>> +       of_property_read_u8(np, "ti,davinci-cs-rsetup", &data->rsetup);
>> +       of_property_read_u8(np, "ti,davinci-cs-whold", &data->whold);
>> +       of_property_read_u16(np, "ti,davinci-cs-wstrobe", &data->wstrobe);
>> +       of_property_read_u8(np, "ti,davinci-cs-wsetup", &data->wsetup);
>> +       if (!of_property_read_u32(np, "ti,bus-width", &val))
>> +               if (val == 16)
>> +                       data->asize = 1;
>> +       data->enable_ew = of_property_read_bool(np, "ti,davinci-cs-ew");
>> +       data->enable_ss = of_property_read_bool(np, "ti,davinci-cs-ss");
>> +       return 0;
>> +}
>> +
>> +static const struct of_device_id davinci_aemif_of_match[] = {
>> +       { .compatible = "ti,davinci-aemif", },
>> +       { .compatible = "ti,keystone-aemif", },
>> +       { .compatible = "ti,omap-L138-aemif", },
> 
> Please use ti,da850-aemif instead. We dont use the omap-like paper part
> number for these devices in kernel to avoid confusion with real OMAP
> devices.
> 

Ok, I'll replace ti,omap-L138-aemif -> ti,da850-aemif

>> +       {},
>> +};
>> +
>> +static const struct of_device_id davinci_cs_of_match[] = {
>> +       { .compatible = "ti,davinci-cs", },
>> +       {},
>> +};
>> +
>> +static int davinci_aemif_probe(struct platform_device *pdev)
>> +{
>> +       int ret  = -ENODEV, i;
>> +       struct resource *res;
>> +       struct device *dev = &pdev->dev;
>> +       struct device_node *np = dev->of_node;
>> +
>> +       if (np == NULL)
>> +               return 0;
>> +
>> +       if (aemif) {
>> +               dev_err(dev, "davinci_aemif driver is in use currently\n");
>> +               return -EBUSY;
>> +       }
> 
> Why expressly prevent multiple AEMIF devices? Its entirely conceivable
> to have two memories like NAND and NOR flash connect to two different
> AEMIF interfaces.
> 

It can be, but I'm not sure if it is needed. Currently I've not seen case where
more than 2 cses were used, I mean we have 2 cs free, why do we need the second AEMIF
controller?

>> +
>> +       aemif = devm_kzalloc(dev, sizeof(*aemif), GFP_KERNEL);
>> +
>> +       if (!aemif) {
>> +               dev_err(dev, "cannot allocate memory for aemif\n");
>> +               return -ENOMEM;
>> +       }
>> +
>> +       aemif->clk = devm_clk_get(dev, "aemif");
> 
> If this is the only clock you care about, you can use NULL for
> connection id.
> 

Yes I can, I'll replace aemif name on NULL.

>> +       if (IS_ERR(aemif->clk)) {
>> +               dev_err(dev, "cannot get clock 'aemif'\n");
>> +               return PTR_ERR(aemif->clk);
>> +       }
>> +
>> +       clk_prepare_enable(aemif->clk);
>> +       aemif->clk_rate = clk_get_rate(aemif->clk) / 1000;
>> +
>> +       aemif->dev = dev;
>> +
>> +       if (of_device_is_compatible(np, "ti,omap-L138-aemif"))
>> +               aemif->cs_offset = 2;
>> +
>> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +       aemif->base = devm_ioremap_resource(dev, res);
>> +       if (IS_ERR(aemif->base)) {
>> +               ret = PTR_ERR(aemif->base);
>> +               goto error;
>> +       }
>> +
>> +       /*
>> +        * For every controller device node, there is a cs device node that
>> +        * describe the bus configuration parameters. This functions iterate
>> +        * over these nodes and update the cs data array.
>> +        */
>> +       for_each_matching_node(np, of_match_ptr(davinci_cs_of_match)) {
>> +               ret = of_davinci_aemif_parse_abus_config(np);
>> +               if (ret < 0)
>> +                       goto error;
>> +       }
>> +
>> +       for (i = 0; i < aemif->num_cs; i++) {
>> +               ret = davinci_aemif_config_abus(&aemif->cs_data[i]);
>> +               if (ret < 0) {
>> +                       dev_err(dev, "Error configuring chip select %d\n",
>> +                               aemif->cs_data[i].cs);
>> +                       goto error;
>> +               }
>> +       }
>> +
>> +       /*
>> +        * Create a child devices explicitly from here to
>> +        * guarantee that the child will be probed after the AEMIF timing
>> +        * parameters are set.
>> +        */
>> +       for_each_matching_node(np, of_match_ptr(davinci_cs_of_match)) {
>> +               ret = of_platform_populate(np, NULL, NULL, dev);
>> +               if (ret < 0)
>> +                       goto error;
>> +       }
>> +
>> +       return 0;
>> +error:
>> +       clk_disable_unprepare(aemif->clk);
>> +       return ret;
>> +}
>> +
>> +static int davinci_aemif_remove(struct platform_device *pdev)
>> +{
>> +       clk_disable_unprepare(aemif->clk);
>> +       return 0;
>> +}
>> +
>> +static struct platform_driver davinci_aemif_driver = {
>> +       .probe = davinci_aemif_probe,
>> +       .remove = davinci_aemif_remove,
>> +       .driver = {
>> +               .name = DRV_NAME,
>> +               .owner = THIS_MODULE,
>> +               .of_match_table = of_match_ptr(davinci_aemif_of_match),
>> +       },
>> +};
>> +
>> +module_platform_driver(davinci_aemif_driver);
>> +
>> +MODULE_AUTHOR("Murali Karicheri <[email-masked]>");
> 
> Is this correct? If yes, I would have expected him to sign-off on the
> patch too. If not, please drop this.

I will add sign-off

> Thanks,
> Sekhar

-- 
Regards,
Ivan Khoronzhuk