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

[Sean Anderson]

On 6/4/21 12:52 AM, Tianrui Wei wrote:
> From: Tianrui Wei <tianrui-wei at 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 at outlook.com>
> Signed-off-by: Jonathan Balkind <jbalkind at 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 ;)

> +    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.

> +
>   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 at samsung.com>
> + * Jaehoon Chung <jh80.chung at 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 at 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 *.

> +};
> +
> +/*
> + * see mmc_read_blocks to see how it is used.
> + * start block is hidden at cmd->arg

Hidden?

> + * 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

> +{
> +	/* check first if this is a pure command */
> +	if (!data)
> +		return 0;

Variable declarations come before code.

> +
> +	u64 byte_cnt, start_block, start_addr;

I think these should be size_t, since you use it for pointer
arithmetic.

> +
> +	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)?

> +	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:

> Scratch the previous email, I stand corrected. You're right about
> memcpy could work, thanks for the great suggestion :P 

What happened to that?

> +			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.

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.

--Sean


[1] https://u-boot.readthedocs.io/en/latest/develop/driver-model/design.html#error-codes

> +	}
> +
> +	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),
> +};
>