Re: [PATCH V5 1/2] mmc: add OpenPiton mmc support

[Sean Anderson <seanga2@gmail.com>]

On 6/6/21 12:57 PM, Tianrui Wei wrote:
> Dear Sean,
> 
> Many thanks for taking the time and energy to review our patches ( again )
> And sorry about not responding or not implementing them. I'll go through
> them one by one and try to doing so in the future :P
> 
> On 6/7/21 12:34 AM, Sean Anderson wrote:
>> On 6/4/21 12:52 AM, Tianrui Wei wrote:
>>> From: Tianrui Wei <tianrui-wei@outlook.com>
>>> Date: Fri, 4 June 2021 12:45:29 +0800
>>> Subject: [PATCH v5 1/2] mmc: add OpenPiton mmc support
>>>
>>> This patch adds mmc support for OpenPiton board.
>>>
>>> Changelog:
>>>
>>> v5: move definitions around, changed some incompatible type information
>>>
>>> Signed-off-by: Tianrui Wei <tianrui-wei@outlook.com>
>>> Signed-off-by: Jonathan Balkind <jbalkind@ucsb.edu>
>>> ---
>>>
>>>    drivers/mmc/Kconfig                     |   7 +
>>>    drivers/mmc/Makefile                    |   1 +
>>>    drivers/mmc/piton_mmc.c                 | 174 +++++
>>>    3 files changed, 182 insertions(+)
>>>    create mode 100644 drivers/mmc/piton_mmc.c
>>>
>>> diff --git a/drivers/mmc/Kconfig b/drivers/mmc/Kconfig
>>> index 14d79139..1038800f 100644
>>> --- a/drivers/mmc/Kconfig
>>> +++ b/drivers/mmc/Kconfig
>>> @@ -707,6 +707,13 @@ config MMC_SUNXI_HAS_MODE_SWITCH
>>>        bool
>>>        depends on MMC_SUNXI
>>>    +config MMC_PITON
>>> +    bool "MMC support for openpiton SoC"
>>> +  depends on DM_MMC && BLK
>>> +    help
>>> +    This driver enables SD card support in U-Boot port for
>>
>> We already know it's for U-Boot ;)
> 
> :P
> 
>>
>>> +    OpenPiton SoC
>>
>> Please add a bit more than this. In particular, it would be useful to
>> note that this is an "emulated" device where the host does all of the
>> work.
> 
> Will do :P
> 
>>
>>> +
>>>    config GENERIC_ATMEL_MCI
>>>        bool "Atmel Multimedia Card Interface support"
>>>        depends on DM_MMC && BLK && ARCH_AT91
>>> diff --git a/drivers/mmc/Makefile b/drivers/mmc/Makefile
>>> index 1c849cba..698dfe05 100644
>>> --- a/drivers/mmc/Makefile
>>> +++ b/drivers/mmc/Makefile
>>> @@ -71,6 +71,7 @@ obj-$(CONFIG_MMC_SDHCI_XENON)        += xenon_sdhci.o
>>>    obj-$(CONFIG_MMC_SDHCI_ZYNQ)        += zynq_sdhci.o
>>>      obj-$(CONFIG_MMC_SUNXI)            += sunxi_mmc.o
>>> +obj-$(CONFIG_MMC_PITON)         += piton_mmc.o
>>>    obj-$(CONFIG_MMC_UNIPHIER)        += tmio-common.o uniphier-sd.o
>>>    obj-$(CONFIG_RENESAS_SDHI)        += tmio-common.o renesas-sdhi.o
>>>    obj-$(CONFIG_MMC_BCM2835)        += bcm2835_sdhost.o
>>> diff --git a/drivers/mmc/piton_mmc.c b/drivers/mmc/piton_mmc.c
>>> new file mode 100644
>>> index 00000000..2b2d5756
>>> --- /dev/null
>>> +++ b/drivers/mmc/piton_mmc.c
>>> @@ -0,0 +1,174 @@
>>> +// SPDX-License-Identifier: GPL-2.0+
>>> +/*
>>> + * (C) Copyright 2009 SAMSUNG Electronics
>>> + * Minkyu Kang <mk7.kang@samsung.com>
>>> + * Jaehoon Chung <jh80.chung@samsung.com>
>>> + * Portions Copyright 2011-2019 NVIDIA Corporation
>>> + * Portions Copyright 2021 Tianrui Wei
>>> + * This file is adapted from tegra_mmc.c
>>> + * Tianrui Wei <tianrui-wei@outlook.com>
>>> + */
>>> +
>>> +#include <asm/gpio.h>
>>> +#include <asm/io.h>
>>> +#include <common.h>
>>> +#include <dm.h>
>>> +#include <errno.h>
>>> +#include <linux/bitops.h>
>>> +#include <linux/types.h>
>>> +#include <linux/delay.h>
>>> +#include <linux/err.h>
>>> +#include <log.h>
>>> +#include <div64.h>
>>> +#include <mmc.h>
>>> +
>>> +struct piton_mmc_plat {
>>> +    struct mmc_config cfg;
>>> +    struct mmc mmc;
>>> +};
>>> +
>>> +struct piton_mmc_priv {
>>> +    u64 piton_mmc_base_addr; /* peripheral id */
>>
>> Again, please use void __iomem *.
> 
> Sorry, forgot this change :(
> 
>>
>>> +};
>>> +
>>> +/*
>>> + * see mmc_read_blocks to see how it is used.
>>> + * start block is hidden at cmd->arg
>>
>> Hidden?
> 
> I wrote this comment a long time ago, I'll comment it out.
> 
>>
>>> + * also, initialize the block size at init
>>> + */
>>> +static int piton_mmc_send_cmd(struct udevice *dev, struct mmc_cmd *cmd,
>>> +                              struct mmc_data *data)
>>
>> Nit: alignment
> 
> I'm not sure how to align this? Should I align the struct in the first line
> and the second line? It appears so in my email client :P

In your original email, this second line has 7 tabs, whereas the line
above it has 29 characters before the `(`. I'm not sure why it's aligned
in my reply. You can see the misaligned issue if you view your patch in
patchwork.

> 
>>
>>> +{
>>> +    /* check first if this is a pure command */
>>> +    if (!data)
>>> +        return 0;
>>
>> Variable declarations come before code.
> 
> Will do :P
> 
>>
>>> +
>>> +    u64 byte_cnt, start_block, start_addr;
>>
>> I think these should be size_t, since you use it for pointer
>> arithmetic.
> 
> Will do :P
> 
>>
>>> +
>>> +    struct piton_mmc_priv *priv = dev_get_priv(dev);
>>> +    unsigned long *buff = (unsigned long *)data->dest;
>>> +
>>> +    start_addr = priv->piton_mmc_base_addr + (start_block);
>>> +    byte_cnt = data->blocks * data->blocksize;
>>
>> What should happen if (byte_cnt & 3)?
> 
> The 1th or 3rd byte will be read into buf,

Ah, disregard this; presumably blocksize will always be a (large enough)
power of two.

> 
>>
>>> +    start_block = cmd->cmdarg;
>>> +
>>> +    /* if there is a read */
>>> +    if (data->flags & MMC_DATA_READ) {
>>> +        for (u64 i = 0; i < byte_cnt; i += 4) {
>>
>> Declare i with the rest of the variables.
>>
>>> +            *(buff) = readl((void *)(start_addr + i));
>>
>> I think this could be rewritten as
>>
>> size_t byte_cnt;
>> u32 *buff, *start_addr;
>>
>> /* ... */
>>
>> for (byte_cnt = /* ... */; byte_cnt; byte_cnt -= sizeof(u32));
>>      *buff++ = readl(start_addr++);
>>
>> Which more closely follows the model of memcpy. Speaking of which, I
>> thought you were going to use it:
> 
> Thanks for the style suggestion :P I'll use that
> 
>>
>>> Scratch the previous email, I stand corrected. You're right about
>>> memcpy could work, thanks for the great suggestion :P
>>
>> What happened to that?
> 
> I checked with Professor Balkind regarding memcpy, and there were some
> issues with it because it's accessing an I/O device we need to maintain
> particular alignment which memcpy might not do, so we're sticking with
> the old implementation.

Ok.

> 
>>
>>> +            buff++;
>>> +        }
>>> +    } else {
>>> +        /* else there is a write
>>> +         * we don't handle write, so error right away
>>> +         */
>>> +        return -ENODEV;
>>
>> Please use -ENOSYS. See [1] for details.
> 
> Will do :P
> 
>>
>> In general, several of my comments on your previous patch are still
>> unaddressed. I would like if you could either respond to them with your
>> reasoning for not addressing them, or implement them.
> 
> Will definitely do that in the future :P
> 
> Tianrui
> 
>>
>> --Sean
>>
>>
>> [1] https://apac01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fu-boot.readthedocs.io%2Fen%2Flatest%2Fdevelop%2Fdriver-model%2Fdesign.html%23error-codes&amp;data=04%7C01%7C%7Cf72fe8fce39746732fdd08d92908e60b%7C84df9e7fe9f640afb435aaaaaaaaaaaa%7C1%7C0%7C637585940462351512%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=ncVph6yZoK4UaDnH2f3js3dsxtwNWih1fhI%2BwCq6jfw%3D&amp;reserved=0
>>
>>> +    }
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +static int piton_mmc_ofdata_to_platdata(struct udevice *dev)
>>> +{
>>> +    struct piton_mmc_priv *priv = dev_get_priv(dev);
>>> +    struct piton_mmc_plat *plat = dev_get_platdata(dev);
>>> +    struct mmc_config *cfg;
>>> +    struct mmc *mmc;
>>> +    /* fill in device description */
>>> +    struct blk_desc *bdesc;
>>> +
>>> +    priv->piton_mmc_base_addr = dev_read_addr(dev);
>>> +    cfg = &plat->cfg;
>>> +    cfg->name = "PITON MMC";
>>> +    cfg->host_caps = MMC_MODE_8BIT;
>>> +    cfg->f_max = 100000;
>>> +    cfg->f_min = 400000;
>>> +    cfg->voltages = MMC_VDD_21_22;
>>> +
>>> +    mmc = &plat->mmc;
>>> +    mmc->read_bl_len = MMC_MAX_BLOCK_LEN;
>>> +    mmc->capacity_user = 0x100000000;
>>> +    mmc->capacity_user *= mmc->read_bl_len;
>>> +    mmc->capacity_boot = 0;
>>> +    mmc->capacity_rpmb = 0;
>>> +    for (int i = 0; i < 4; i++)
>>> +        mmc->capacity_gp[i] = 0;
>>> +    mmc->capacity = 0x2000000000ULL;
>>> +    mmc->has_init = 1;
>>> +
>>> +    bdesc = mmc_get_blk_desc(mmc);
>>> +    bdesc->lun = 0;
>>> +    bdesc->hwpart = 0;
>>> +    bdesc->type = 0;
>>> +    bdesc->blksz = mmc->read_bl_len;
>>> +    bdesc->log2blksz = LOG2(bdesc->blksz);
>>> +    bdesc->lba = lldiv(mmc->capacity, mmc->read_bl_len);
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +/* test if piton has the micro mmc card present
>>> + * always return 1, which means present
>>> + */
>>> +static int piton_mmc_getcd(struct udevice *dev)
>>> +{
>>> +    /*
>>> +     * always return 1
>>> +     */
>>> +    return 1;
>>> +}
>>> +
>>> +/* dummy function, piton_mmc don't need initialization
>>> + * in hw
>>> + */
>>> +static const struct dm_mmc_ops piton_mmc_ops = {
>>> +    .send_cmd = piton_mmc_send_cmd,
>>> +    .get_cd = piton_mmc_getcd,
>>> +};
>>> +
>>> +static int piton_mmc_probe(struct udevice *dev)
>>> +{
>>> +    struct mmc_uclass_priv *upriv = dev_get_uclass_priv(dev);
>>> +    struct piton_mmc_plat *plat = dev_get_platdata(dev);
>>> +    struct mmc_config *cfg = &plat->cfg;
>>> +
>>> +    cfg->name = dev->name;
>>> +    upriv->mmc = &plat->mmc;
>>> +    upriv->mmc->has_init = 1;
>>> +    upriv->mmc->capacity = 0x2000000000ULL;
>>> +    upriv->mmc->read_bl_len = MMC_MAX_BLOCK_LEN;
>>> +
>>> +    return 0;
>>> +}
>>> +
>>> +static int piton_mmc_bind(struct udevice *dev)
>>> +{
>>> +    struct piton_mmc_plat *plat = dev_get_platdata(dev);
>>> +    struct mmc_config *cfg = &plat->cfg;
>>> +
>>> +    cfg->name = dev->name;
>>> +    cfg->host_caps = MMC_MODE_HS_52MHz | MMC_MODE_HS | MMC_MODE_8BIT;
>>> +    cfg->voltages = MMC_VDD_165_195 | MMC_VDD_32_33 | MMC_VDD_33_34;
>>> +    cfg->f_min = 1000000;
>>> +    cfg->f_max = 52000000;
>>> +    cfg->b_max = U32_MAX;
>>> +
>>> +    return mmc_bind(dev, &plat->mmc, cfg);
>>> +}
>>> +
>>> +static const struct udevice_id piton_mmc_ids[] = {
>>> +        {.compatible = "openpiton,piton-mmc"},
>>> +        { /* sentinel */ }
>>> +};
>>> +
>>> +U_BOOT_DRIVER(piton_mmc_drv) = {
>>> +    .name = "piton_mmc",
>>> +    .id = UCLASS_MMC,
>>> +    .of_match = piton_mmc_ids,
>>> +    .ofdata_to_platdata = piton_mmc_ofdata_to_platdata,
>>> +    .bind = piton_mmc_bind,
>>> +    .probe = piton_mmc_probe,
>>> +    .ops = &piton_mmc_ops,
>>> +    .platdata_auto_alloc_size = sizeof(struct piton_mmc_plat),
>>> +    .priv_auto_alloc_size = sizeof(struct piton_mmc_priv),
>>> +};
>>>
>>