On Wed 06 Apr 05:34 PDT 2016, Keguang Zhang wrote:
> From: Kelvin Cheung <keguang.zhang@xxxxxxxxx>
>
> This patch adds NAND driver for Loongson1B.
>
Hi Keguang,
Please find some comments inline.
> Signed-off-by: Kelvin Cheung <keguang.zhang@xxxxxxxxx>
> ---
> drivers/mtd/nand/Kconfig | 8 +
> drivers/mtd/nand/Makefile | 1 +
> drivers/mtd/nand/loongson1_nand.c | 519 ++++++++++++++++++++++++++++++++++++++
> 3 files changed, 528 insertions(+)
> create mode 100644 drivers/mtd/nand/loongson1_nand.c
>
> diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig
> index f05e0e9..d90f545 100644
> --- a/drivers/mtd/nand/Kconfig
> +++ b/drivers/mtd/nand/Kconfig
> @@ -563,4 +563,12 @@ config MTD_NAND_QCOM
> Enables support for NAND flash chips on SoCs containing the EBI2 NAND
> controller. This controller is found on IPQ806x SoC.
>
> +config MTD_NAND_LOONGSON1
> + tristate "Support for Loongson1 SoC NAND controller"
> + depends on MACH_LOONGSON32
> + select DMADEVICES
> + select DMA_LOONGSON1
> + help
> + Enables support for NAND Flash on Loongson1 SoC based boards.
Indent the help text with 2 spaces beyond the "help".
> +
> endif # MTD_NAND
[..]
> diff --git a/drivers/mtd/nand/loongson1_nand.c b/drivers/mtd/nand/loongson1_nand.c
[..]
> +
> +/* macros for registers read/write */
> +#define nand_readl(nand, off) \
> + __raw_readl((nand)->reg_base + (off))
> +
> +#define nand_writel(nand, off, val) \
> + __raw_writel((val), (nand)->reg_base + (off))
Why are you using the __raw variants here? Are these registers following
the endian that the cpu happens to run in?
> +
> +#define set_cmd(nand, ctrl) \
> + nand_writel(nand, NAND_CMD, ctrl)
> +
> +#define start_nand(nand) \
> + nand_writel(nand, NAND_CMD, nand_readl(nand, NAND_CMD) | CMD_VALID)
You have a single user of these two macros, just inline them.
Further more, it's easier to read if you split the later into a clear:
val = nand_readl(nand, NAND_CMD);
val |= CMD_VALID;
nand_writel(nand, NAND_CMD, val);
And in my eyes:
nand_readl(nand, NAND_CMD)
isn't cleaner than:
readl(nand->reg_base + NAND_CMD)
And you have this construct in several places already, so I would say
just skip all these macros.
> +
> +struct ls1x_nand {
> + struct platform_device *pdev;
You don't use pdev anywhere.
> + struct nand_chip chip;
> +
> + struct clk *clk;
> + void __iomem *reg_base;
> +
> + int cmd_val;
This is only assigned in ls1x_nand_cmdfunc() and it will either get a
value based on the command or if the command is NAND_CMD_PAGEPROG it
will use the value 0 from a previous run.
So you should make this a local variable.
> + char datareg[8];
> + char *data_ptr;
These should be uint8_t based on how you're using them.
> +
> + /* DMA stuff */
> + unsigned char *dma_buf;
void *
> + unsigned int buf_off;
> + unsigned int buf_len;
> +
> + /* DMA Engine stuff */
> + unsigned int dma_chan_id;
> + struct dma_chan *dma_chan;
> + dma_cookie_t dma_cookie;
> + struct completion dma_complete;
> + void __iomem *dma_desc;
dma_desc is unused.
> +};
> +
> +static void dma_callback(void *data)
> +{
> + struct ls1x_nand *nand = (struct ls1x_nand *)data;
No typecast needed from void *
> + struct mtd_info *mtd = nand_to_mtd(&nand->chip);
> + struct dma_tx_state state;
> + enum dma_status status;
> +
> + status = dmaengine_tx_status(nand->dma_chan, nand->dma_cookie, &state);
iirc you can pass NULL instead of state if you don't care about the
result.
> + if (likely(status == DMA_COMPLETE))
> + dev_dbg(mtd->dev.parent, "DMA complete with cookie=%d\n",
> + nand->dma_cookie);
> + else
> + dev_err(mtd->dev.parent, "DMA error with cookie=%d\n",
> + nand->dma_cookie);
> +
> + complete(&nand->dma_complete);
Don't you want to propagate this error to the "caller"?
Do note that when this happens in some product, no-one will be there to
see this error message and do something about it.
> +}
> +
> +static int setup_dma(struct ls1x_nand *nand)
> +{
> + struct mtd_info *mtd = nand_to_mtd(&nand->chip);
> + struct dma_slave_config cfg;
> + dma_cap_mask_t mask;
> + int ret;
> +
> + /* allocate DMA buffer */
> + nand->dma_buf = devm_kzalloc(mtd->dev.parent,
> + mtd->writesize + mtd->oobsize, GFP_KERNEL);
> + if (!nand->dma_buf)
> + return -ENOMEM;
> +
> + dma_cap_zero(mask);
> + dma_cap_set(DMA_SLAVE, mask);
> + nand->dma_chan = dma_request_channel(mask, ls1x_dma_filter_fn,
> + &nand->dma_chan_id);
> + if (!nand->dma_chan) {
> + dev_err(mtd->dev.parent, "failed to request DMA channel\n");
> + return -EBUSY;
> + }
> + dev_info(mtd->dev.parent, "got %s for %s access\n",
> + dma_chan_name(nand->dma_chan), dev_name(mtd->dev.parent));
dev_info will include the name already, no need to print it twice.
> +
> + cfg.src_addr = CPHYSADDR(nand->reg_base + NAND_DMA_ADDR);
> + cfg.dst_addr = CPHYSADDR(nand->reg_base + NAND_DMA_ADDR);
> + cfg.src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
> + cfg.dst_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES;
> + ret = dmaengine_slave_config(nand->dma_chan, &cfg);
> + if (ret) {
> + dev_err(mtd->dev.parent, "failed to config DMA channel\n");
> + dma_release_channel(nand->dma_chan);
> + return ret;
> + }
> +
> + init_completion(&nand->dma_complete);
> +
> + return 0;
> +}
> +
> +static int start_dma(struct ls1x_nand *nand, unsigned int len, bool is_write)
> +{
> + struct mtd_info *mtd = nand_to_mtd(&nand->chip);
> + struct dma_chan *chan = nand->dma_chan;
> + struct dma_async_tx_descriptor *desc;
> + enum dma_data_direction data_dir =
> + is_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE;
> + enum dma_transfer_direction xfer_dir =
> + is_write ? DMA_MEM_TO_DEV : DMA_DEV_TO_MEM;
> + dma_addr_t dma_addr;
> + int ret;
> +
> + dma_addr =
> + dma_map_single(chan->device->dev, nand->dma_buf, len, data_dir);
> + if (dma_mapping_error(chan->device->dev, dma_addr)) {
> + dev_err(mtd->dev.parent, "failed to map DMA buffer\n");
> + return -ENXIO;
> + }
> +
> + desc = dmaengine_prep_slave_single(chan, dma_addr, len, xfer_dir,
> + DMA_PREP_INTERRUPT);
> + if (!desc) {
> + dev_err(mtd->dev.parent,
> + "failed to prepare DMA descriptor\n");
> + ret = PTR_ERR(desc);
> + goto err;
> + }
> + desc->callback = dma_callback;
> + desc->callback_param = nand;
> +
> + nand->dma_cookie = dmaengine_submit(desc);
> + ret = dma_submit_error(nand->dma_cookie);
> + if (ret) {
> + dev_err(mtd->dev.parent,
> + "failed to submit DMA descriptor\n");
> + goto err;
> + }
> +
> + dev_dbg(mtd->dev.parent, "issue DMA with cookie=%d\n",
> + nand->dma_cookie);
> + dma_async_issue_pending(chan);
> +
> + ret = wait_for_completion_timeout(&nand->dma_complete,
> + msecs_to_jiffies(LS1X_NAND_TIMEOUT));
> + if (ret <= 0) {
> + dev_err(mtd->dev.parent, "DMA timeout\n");
> + dmaengine_terminate_all(chan);
> + ret = -EIO;
> + }
> + ret = 0;
You're overwriting the error from the timeout here.
Alsoas I commented in dma_callback, you're propagating any outcome (good
or bad) from the dma operation as a success.
> +err:
> + dma_unmap_single(chan->device->dev, dma_addr, len, data_dir);
> +
> + return ret;
> +}
> +
> +static void ls1x_nand_select_chip(struct mtd_info *mtd, int chip)
> +{
> +}
> +
> +static int ls1x_nand_dev_ready(struct mtd_info *mtd)
> +{
> + struct nand_chip *chip = mtd_to_nand(mtd);
> + struct ls1x_nand *nand = nand_get_controller_data(chip);
> +
> + if (nand_readl(nand, NAND_CMD) & OP_DONE)
> + return 1;
> +
> + return 0;
return !!(nand_readl(nand, NAND_CMD) & OP_DONE);
But preferable:
u32 val;
val = readl(nand->reg_base + NAND_CMD);
return !!(val & OP_DONE);
> +}
> +
> +static uint8_t ls1x_nand_read_byte(struct mtd_info *mtd)
> +{
> + struct nand_chip *chip = mtd_to_nand(mtd);
> + struct ls1x_nand *nand = nand_get_controller_data(chip);
> +
> + return *(nand->data_ptr++);
Are there any guarantees that this won't ever happen more than 8 times
(and read outside datareg)?
> +}
> +
[..]
> +
> +static void ls1x_nand_cmdfunc(struct mtd_info *mtd, unsigned int command,
> + int column, int page_addr)
> +{
> + struct nand_chip *chip = mtd_to_nand(mtd);
> + struct ls1x_nand *nand = nand_get_controller_data(chip);
> +
> + dev_dbg(mtd->dev.parent, "cmd = 0x%02x, col = 0x%08x, page = 0x%08x\n",
> + command, column, page_addr);
> +
> + if (command == NAND_CMD_RNDOUT) {
> + nand->buf_off = column;
> + return;
> + }
> +
> + /*set address, buffer length and buffer offset */
> + if (column != -1 || page_addr != -1)
> + set_addr_len(mtd, command, column, page_addr);
> +
> + /*prepare NAND command */
> + switch (command) {
> + case NAND_CMD_RESET:
> + nand->cmd_val = CMD_RESET;
> + break;
> + case NAND_CMD_STATUS:
> + nand->cmd_val = CMD_STATUS;
> + break;
> + case NAND_CMD_READID:
> + nand->cmd_val = CMD_READID;
> + break;
> + case NAND_CMD_READ0:
> + nand->cmd_val = OP_SPARE | OP_MAIN | CMD_READ;
> + break;
> + case NAND_CMD_READOOB:
> + nand->cmd_val = OP_SPARE | CMD_READ;
> + break;
> + case NAND_CMD_ERASE1:
> + nand->cmd_val = CMD_ERASE;
> + break;
> + case NAND_CMD_PAGEPROG:
You can make cmd_val a local variable to this function if you set it to
0 here.
> + break;
> + case NAND_CMD_SEQIN:
> + if (column < mtd->writesize)
> + nand->cmd_val = OP_SPARE | OP_MAIN | CMD_WRITE;
> + else
> + nand->cmd_val = OP_SPARE | CMD_WRITE;
> + default:
> + return;
> + }
> +
> + /*set NAND command */
> + set_cmd(nand, nand->cmd_val);
> + /*trigger NAND operation */
> + start_nand(nand);
It would be clearer what's going on here if you didn't hide the writel
calls behind macros.
> + /*trigger DMA for R/W operation */
> + if (command == NAND_CMD_READ0 || command == NAND_CMD_READOOB)
> + start_dma(nand, nand->buf_len, false);
> + else if (command == NAND_CMD_PAGEPROG)
> + start_dma(nand, nand->buf_len, true);
> + nand_wait_ready(mtd);
> +
> + if (command == NAND_CMD_STATUS) {
> + nand->datareg[0] = (char)(nand_readl(nand, NAND_STATUS) >> 8);
> + /*work around hardware bug for invalid STATUS */
> + nand->datareg[0] |= 0xc0;
> + nand->data_ptr = nand->datareg;
> + } else if (command == NAND_CMD_READID) {
> + nand->datareg[0] = (char)(nand_readl(nand, NAND_IDH));
> + nand->datareg[1] = (char)(nand_readl(nand, NAND_IDL) >> 24);
> + nand->datareg[2] = (char)(nand_readl(nand, NAND_IDL) >> 16);
> + nand->datareg[3] = (char)(nand_readl(nand, NAND_IDL) >> 8);
> + nand->datareg[4] = (char)(nand_readl(nand, NAND_IDL));
> + nand->data_ptr = nand->datareg;
> + }
This is essentially a 4 case switch statement, hidden in two chunks of
conditionals.
> +
> + nand->cmd_val = 0;
> +}
> +
> +static void nand_hw_init(struct ls1x_nand *nand, int hold_cycle, int wait_cycle)
> +{
> + struct nand_chip *chip = &nand->chip;
> + struct mtd_info *mtd = nand_to_mtd(chip);
> + int chipsize = (int)(chip->chipsize >> 20);
> + int cell_size = 0x0;
> +
> + switch (chipsize) {
> + case SZ_128: /*128M */
> + cell_size = 0x0;
> + break;
> + case SZ_256: /*256M */
> + cell_size = 0x1;
> + break;
> + case SZ_512: /*512M */
> + cell_size = 0x2;
> + break;
> + case SZ_1K: /*1G */
> + cell_size = 0x3;
> + break;
> + case SZ_2K: /*2G */
> + cell_size = 0x4;
> + break;
> + case SZ_4K: /*4G */
> + cell_size = 0x5;
> + break;
> + case SZ_8K: /*8G */
> + cell_size = 0x6;
> + break;
> + case SZ_16K: /*16G */
> + cell_size = 0x7;
> + break;
> + default:
> + dev_warn(mtd->dev.parent, "unsupported chip size: %d MB\n",
> + chipsize);
You should probably not continue here and just assume that you have a
128M chip. Turn this into an dev_err and return an error value to your
probe.
> + }
> +
> + nand_writel(nand, NAND_TIMING, (hold_cycle << 8) | wait_cycle);
> + nand_writel(nand, NAND_PARAM,
> + (nand_readl(nand, NAND_PARAM) & 0xfffff0ff) | (cell_size <<
> + 8));
This would be much cleaner if written as:
val = readl()
val &= ~0x00000f00;
val |= cell_size << 8;
writel(val);
And preferably a define that names the mask of bit 8 to 11 in this
register.
> +}
> +
> +static int ls1x_nand_probe(struct platform_device *pdev)
> +{
> + struct device *dev = &pdev->dev;
> + struct plat_ls1x_nand *pdata = dev_get_platdata(dev);
> + struct ls1x_nand *nand;
> + struct mtd_info *mtd;
> + struct nand_chip *chip;
> + struct resource *res;
> + int ret = 0;
> +
> + if (!pdata) {
> + dev_err(dev, "platform data missing\n");
> + return -EINVAL;
> + }
> +
> + nand = devm_kzalloc(dev, sizeof(struct ls1x_nand), GFP_KERNEL);
> + if (!nand)
> + return -ENOMEM;
> + nand->pdev = pdev;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (!res) {
> + dev_err(dev, "failed to get I/O memory\n");
> + return -ENXIO;
> + }
No need to handle the errors from platform_get_resource() when followed
by a devm_ioremap_resource(), as this will error early if res is NULL.
> +
> + nand->reg_base = devm_ioremap_resource(dev, res);
> + if (IS_ERR(nand->reg_base))
> + return PTR_ERR(nand->reg_base);
> +
> + res = platform_get_resource(pdev, IORESOURCE_DMA, 0);
> + if (!res) {
> + dev_err(dev, "failed to get DMA information\n");
> + return -ENXIO;
> + }
> + nand->dma_chan_id = res->start;
> +
> + nand->clk = devm_clk_get(dev, pdev->name);
> + if (IS_ERR(nand->clk)) {
> + dev_err(dev, "failed to get %s clock\n", pdev->name);
> + return PTR_ERR(nand->clk);
> + }
> + clk_prepare_enable(nand->clk);
> +
> + chip = &nand->chip;
> + chip->read_byte = ls1x_nand_read_byte;
> + chip->read_buf = ls1x_nand_read_buf;
> + chip->write_buf = ls1x_nand_write_buf;
> + chip->select_chip = ls1x_nand_select_chip;
> + chip->dev_ready = ls1x_nand_dev_ready;
> + chip->cmdfunc = ls1x_nand_cmdfunc;
> + chip->options = NAND_NO_SUBPAGE_WRITE;
> + chip->ecc.mode = NAND_ECC_SOFT;
> + nand_set_controller_data(chip, nand);
> +
> + mtd = nand_to_mtd(chip);
> + mtd->name = "ls1x-nand";
> + mtd->owner = THIS_MODULE;
> + mtd->dev.parent = dev;
> +
> + ret = nand_scan_ident(mtd, 1, NULL);
> + if (ret)
> + goto err;
> +
> + nand_hw_init(nand, pdata->hold_cycle, pdata->wait_cycle);
> +
> + ret = setup_dma(nand);
> + if (ret)
> + goto err;
> +
> + ret = nand_scan_tail(mtd);
> + if (ret)
> + goto err;
> +
> + ret = mtd_device_register(mtd, pdata->parts, pdata->nr_parts);
> + if (ret) {
> + dev_err(dev, "failed to register MTD device: %d\n", ret);
> + goto err;
> + }
> +
> + platform_set_drvdata(pdev, nand);
> + dev_info(dev, "Loongson1 NAND driver registered\n");
I prefer not have every driver advertising their existence in the kernel
log, keeps things cleaner. If you want a easy way for debugging purposes
you can make it a dev_dbg (instead of just removing it) and use
DYNAMIC_DEBUG to enable that from the command line.
> +
> + return 0;
> +err:
> + clk_disable_unprepare(nand->clk);
> +
> + return ret;
> +}
> +
[..]
> +
> +static struct platform_driver ls1x_nand_driver = {
> + .probe = ls1x_nand_probe,
> + .remove = ls1x_nand_remove,
> + .driver = {
> + .name = "ls1x-nand",
> + .owner = THIS_MODULE,
You shouldn't set owner on your platform_driver, it's done for you by
the module_platform_driver() macro.
> + },
> +};
> +
> +module_platform_driver(ls1x_nand_driver);
> +
Regards,
Bjorn
