Re: [PATCH v13 2/2] mtd: rawnand: Add NAND controller support on Intel LGM SoC

[Andy Shevchenko]

On Thu, Sep 17, 2020 at 08:33:08AM +0800, Ramuthevar,Vadivel MuruganX wrote:
> From: Ramuthevar Vadivel Murugan <vadivel.muruganx.ramuthevar@xxxxxxxxxxxxxxx>
> 
> This patch adds the new IP of Nand Flash Controller(NFC) support
> on Intel's Lightning Mountain(LGM) SoC.
> 
> DMA is used for burst data transfer operation, also DMA HW supports
> aligned 32bit memory address and aligned data access by default.
> DMA burst of 8 supported. Data register used to support the read/write
> operation from/to device.
> 
> NAND controller driver implements ->exec_op() to replace legacy hooks,
> these specific call-back method to execute NAND operations.

...

> +#include <linux/clk.h>
> +#include <linux/completion.h>
> +#include <linux/dmaengine.h>
> +#include <linux/dma-direction.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/err.h>
> +#include <linux/init.h>

> +#include <linux/io.h>
> +#include <linux/iopoll.h>

io.h is guaranteed to be included by iopoll.h.

> +#include <linux/kernel.h>
> +#include <linux/platform_device.h>
> +#include <linux/module.h>

> +#include <linux/mtd/mtd.h>
> +#include <linux/mtd/rawnand.h>
> +#include <linux/mtd/nand_ecc.h>
> +#include <linux/mtd/nand.h>

Since mtd is a hosting framework for this driver, I would move this group of headers after more generic ones with a blank line in between.


> +#include <linux/resource.h>

And this I think is guaranteed to be included by io.h.

> +#include <linux/sched.h>
> +#include <linux/slab.h>
> +#include <linux/types.h>

> +#include <linux/platform_device.h>

Dup? It's exactly the reason how alphabetical order can help.

...

> +#define EBU_ADDR_SEL(n)		(0x20 + (n) * 4)

I think 0x20 is an offset here, and better to have it as 0x020 to be consistent
with all other offsets.

...

> +#define EBU_BUSCON(n)		(0x60 + (n) * 4)

Ditto.

...

> +static void ebu_nand_setup_timing(struct ebu_nand_controller *ctrl,
> +				  const struct nand_sdr_timings *timings)
> +{
> +	unsigned int rate = clk_get_rate(ctrl->clk) / 1000000;

HZ_PER_MHZ?

> +	unsigned int period = DIV_ROUND_UP(1000000, rate);

USEC_PER_SEC?

> +	u32 trecov, thold, twrwait, trdwait;
> +	u32 reg = 0;
> +
> +	trecov = DIV_ROUND_UP(max(timings->tREA_max, timings->tREH_min),
> +			      period);
> +	reg |= EBU_BUSCON_RECOVC(trecov);
> +
> +	thold = DIV_ROUND_UP(max(timings->tDH_min, timings->tDS_min), period);
> +	reg |= EBU_BUSCON_HOLDC(thold);
> +
> +	trdwait = DIV_ROUND_UP(max(timings->tRC_min, timings->tREH_min),
> +			       period);
> +	reg |= EBU_BUSCON_WAITRDC(trdwait);
> +
> +	twrwait = DIV_ROUND_UP(max(timings->tWC_min, timings->tWH_min), period);
> +	reg |= EBU_BUSCON_WAITWRC(twrwait);
> +
> +	reg |= EBU_BUSCON_CMULT_V4 | EBU_BUSCON_BCGEN_CS | EBU_BUSCON_ALEC |
> +		EBU_BUSCON_SETUP_EN;
> +
> +	writel(reg, ctrl->ebu + EBU_BUSCON(ctrl->cs_num));
> +}

...

> +	if (oob_required) {
> +		reg = (chip->oob_poi[3] << 24) | (chip->oob_poi[2] << 16) |
> +			(chip->oob_poi[1] << 8) | chip->oob_poi[0];

get_unligned_le32()?

...

> +		reg = (chip->oob_poi[7] << 24) | (chip->oob_poi[6] << 16) |
> +			(chip->oob_poi[5] << 8) | chip->oob_poi[4];

Ditto.

...

> +	ret = readl_poll_timeout_atomic(int_sta, val,
> +					!(val & HSNAND_INT_STA_WR_C), 10, 1000);

Slightly better (logically split between lines):

	ret = readl_poll_timeout_atomic(int_sta, val, !(val & HSNAND_INT_STA_WR_C),
					10, 1000);


> +	if (ret)
> +		return ret;

...

> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "ebunand");
> +	ebu_host->ebu = devm_ioremap_resource(&pdev->dev, res);

Why not to use

	ebu_host->ebu = devm_platform_ioremap_resource_byname(&pdev->dev, "ebunand");

?

> +	if (IS_ERR(ebu_host->ebu))
> +		return PTR_ERR(ebu_host->ebu);
> +
> +	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "hsnand");
> +	ebu_host->hsnand = devm_ioremap_resource(&pdev->dev, res);

Ditto.

> +	if (IS_ERR(ebu_host->hsnand))
> +		return PTR_ERR(ebu_host->hsnand);

...


> +	for (i = 0; i < MAX_CS; i++) {
> +		resname = devm_kasprintf(dev, GFP_KERNEL, "nand_cs%d", i);
> +		res = platform_get_resource_byname(pdev, IORESOURCE_MEM,
> +						   resname);

> +		if (!res)
> +			return -EINVAL;

Redundant check.

> +		ebu_host->cs[i].chipaddr = devm_ioremap_resource(dev, res);

Ditto (see above).

> +		ebu_host->cs[i].nand_pa = res->start;
> +		if (IS_ERR(ebu_host->cs[i].chipaddr))
> +			return PTR_ERR(ebu_host->cs[i].chipaddr);
> +	}

...

> +	ebu_host->clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(ebu_host->clk)) {

> +		ret = PTR_ERR(ebu_host->clk);
> +		dev_err(dev, "failed to get clock: %d\n", ret);
> +		return ret;

	return dev_err_probe() ?

> +	}

...

> +	ebu_host->dma_tx = dma_request_chan(dev, "tx");
> +	if (IS_ERR(ebu_host->dma_tx)) {

> +		ret = PTR_ERR(ebu_host->dma_tx);
> +		dev_err(dev, "DMA tx channel request fail!.\n");
> +		goto err_cleanup_dma;

Ditto. On top why !. ???

> +	}
> +
> +	ebu_host->dma_rx = dma_request_chan(dev, "rx");
> +	if (IS_ERR(ebu_host->dma_rx)) {

> +		ret = PTR_ERR(ebu_host->dma_rx);
> +		dev_err(dev, "DMA rx channel request fail!.\n");
> +		goto err_cleanup_dma;

Ditto.

> +	}

-- 
With Best Regards,
Andy Shevchenko