Date:   Mon, 5 Dec 2016 05:40:17 +0100
From:   Marek Vasut <marek.vasut@...il.com>
To:     Punnaiah Choudary Kalluri <punnaiah.choudary.kalluri@...inx.com>,
        dwmw2@...radead.org, computersforpeace@...il.com,
        boris.brezillon@...e-electrons.com, richard@....at,
        cyrille.pitchen@...el.com, robh+dt@...nel.org, mark.rutland@....com
Cc:     linux-kernel@...r.kernel.org, linux-mtd@...ts.infradead.org,
        devicetree@...r.kernel.org, michals@...inx.com,
        kalluripunnaiahchoudary@...il.com, kpc528@...il.com,
        Punnaiah Choudary Kalluri <punnaia@...inx.com>
Subject: Re: [PATCH v6 2/2] mtd: nand: Add support for Arasan Nand Flash
 Controller

On 12/05/2016 05:11 AM, Punnaiah Choudary Kalluri wrote:
> Added the basic driver for Arasan Nand Flash Controller used in
> Zynq UltraScale+ MPSoC. It supports only Hw Ecc and upto 24bit
> correction.

Ummm, NAND, ECC, can you fix the acronyms to be in caps ?

> Signed-off-by: Punnaiah Choudary Kalluri <punnaia@...inx.com>
> ---
> Chnages in v6:
> - Addressed most of the Brian and Boris comments
> - Separated the nandchip from the nand controller
> - Removed the ecc lookup table from driver
> - Now use framework nand waitfunction and readoob
> - Fixed the compiler warning
> - Adapted the new frameowrk changes related to ecc and ooblayout
> - Disabled the clocks after the nand_reelase
> - Now using only one completion object
> - Boris suggessions like adapting cmd_ctrl and rework on read/write byte
>   are not implemented and i will patch them later
> - Also check_erased_ecc_chunk for erase and check for is_vmalloc_addr will
>   implement later once the basic driver is mainlined. 
> Changes in v5:
> - Renamed the driver filei as arasan_nand.c
> - Fixed all comments relaqted coding style
> - Fixed comments related to propagating the errors
> - Modified the anfc_write_page_hwecc as per the write_page
>   prototype
> Changes in v4:
> - Added support for onfi timing mode configuration
> - Added clock supppport
> - Added support for multiple chipselects
> Changes in v3:
> - Removed unused variables
> - Avoided busy loop and used jifies based implementation
> - Fixed compiler warnings "right shift count >= width of type"
> - Removed unneeded codei and improved error reporting
> - Added onfi version check to ensure reading the valid address cycles
> Changes in v2:
> - Added missing of.h to avoid kbuild system report erro
> ---
>  drivers/mtd/nand/Kconfig       |   8 +
>  drivers/mtd/nand/Makefile      |   1 +
>  drivers/mtd/nand/arasan_nand.c | 974 +++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 983 insertions(+)
>  create mode 100644 drivers/mtd/nand/arasan_nand.c
> 
> diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig
> index 7b7a887..e831f4e 100644
> --- a/drivers/mtd/nand/Kconfig
> +++ b/drivers/mtd/nand/Kconfig
> @@ -569,4 +569,12 @@ config MTD_NAND_MTK
>  	  Enables support for NAND controller on MTK SoCs.
>  	  This controller is found on mt27xx, mt81xx, mt65xx SoCs.
>  
> +config MTD_NAND_ARASAN
> +	tristate "Support for Arasan Nand Flash controller"
> +	depends on HAS_IOMEM
> +	depends on HAS_DMA
> +	help
> +	  Enables the driver for the Arasan Nand Flash controller on
> +	  Zynq UltraScale+ MPSoC.
> +
>  endif # MTD_NAND
> diff --git a/drivers/mtd/nand/Makefile b/drivers/mtd/nand/Makefile
> index cafde6f..44b8b00 100644
> --- a/drivers/mtd/nand/Makefile
> +++ b/drivers/mtd/nand/Makefile
> @@ -58,5 +58,6 @@ obj-$(CONFIG_MTD_NAND_HISI504)	        += hisi504_nand.o
>  obj-$(CONFIG_MTD_NAND_BRCMNAND)		+= brcmnand/
>  obj-$(CONFIG_MTD_NAND_QCOM)		+= qcom_nandc.o
>  obj-$(CONFIG_MTD_NAND_MTK)		+= mtk_nand.o mtk_ecc.o
> +obj-$(CONFIG_MTD_NAND_ARASAN)		+= arasan_nand.o

Keep the list at least reasonably sorted.

>  nand-objs := nand_base.o nand_bbt.o nand_timings.o
> diff --git a/drivers/mtd/nand/arasan_nand.c b/drivers/mtd/nand/arasan_nand.c
> new file mode 100644
> index 0000000..6b0670e
> --- /dev/null
> +++ b/drivers/mtd/nand/arasan_nand.c
> @@ -0,0 +1,974 @@
> +/*
> + * Arasan Nand Flash Controller Driver

NAND

> + * Copyright (C) 2014 - 2015 Xilinx, Inc.

It's 2016 now ...

> + * 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; either version 2 of the License, or (at your
> + * option) any later version.
> + */
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/interrupt.h>
> +#include <linux/io-64-nonatomic-lo-hi.h>
> +#include <linux/module.h>
> +#include <linux/mtd/mtd.h>
> +#include <linux/mtd/nand.h>
> +#include <linux/mtd/partitions.h>
> +#include <linux/of.h>
> +#include <linux/platform_device.h>
> +
> +#define DRIVER_NAME			"arasan_nand"
> +#define EVNT_TIMEOUT			1000

Rename to EVENT_TIMEOUT_<units> to make this less cryptic

> +#define STATUS_TIMEOUT			2000

DTTO

> +#define PKT_OFST			0x00
> +#define MEM_ADDR1_OFST			0x04
> +#define MEM_ADDR2_OFST			0x08
> +#define CMD_OFST			0x0C
> +#define PROG_OFST			0x10
> +#define INTR_STS_EN_OFST		0x14
> +#define INTR_SIG_EN_OFST		0x18
> +#define INTR_STS_OFST			0x1C
> +#define READY_STS_OFST			0x20
> +#define DMA_ADDR1_OFST			0x24
> +#define FLASH_STS_OFST			0x28
> +#define DATA_PORT_OFST			0x30
> +#define ECC_OFST			0x34
> +#define ECC_ERR_CNT_OFST		0x38
> +#define ECC_SPR_CMD_OFST		0x3C
> +#define ECC_ERR_CNT_1BIT_OFST		0x40
> +#define ECC_ERR_CNT_2BIT_OFST		0x44
> +#define DMA_ADDR0_OFST			0x50
> +#define DATA_INTERFACE_REG		0x6C

Why are some things suffixed with _OFST and some with _REG ? Consistency
please. Using ARASAN_ prefix, ie. #define ARASAN_FOO 0xbar to define
regs would be nice.

> +#define PKT_CNT_SHIFT			12
> +
> +#define ECC_ENABLE			BIT(31)
> +#define DMA_EN_MASK			GENMASK(27, 26)
> +#define DMA_ENABLE			0x2
> +#define DMA_EN_SHIFT			26
> +#define REG_PAGE_SIZE_MASK		GENMASK(25, 23)
> +#define REG_PAGE_SIZE_SHIFT		23
> +#define REG_PAGE_SIZE_512		0
> +#define REG_PAGE_SIZE_1K		5
> +#define REG_PAGE_SIZE_2K		1
> +#define REG_PAGE_SIZE_4K		2
> +#define REG_PAGE_SIZE_8K		3
> +#define REG_PAGE_SIZE_16K		4
> +#define CMD2_SHIFT			8
> +#define ADDR_CYCLES_SHIFT		28
> +
> +#define XFER_COMPLETE			BIT(2)
> +#define READ_READY			BIT(1)
> +#define WRITE_READY			BIT(0)
> +#define MBIT_ERROR			BIT(3)
> +#define ERR_INTRPT			BIT(4)
> +
> +#define PROG_PGRD			BIT(0)
> +#define PROG_ERASE			BIT(2)
> +#define PROG_STATUS			BIT(3)
> +#define PROG_PGPROG			BIT(4)
> +#define PROG_RDID			BIT(6)
> +#define PROG_RDPARAM			BIT(7)
> +#define PROG_RST			BIT(8)
> +#define PROG_GET_FEATURE		BIT(9)
> +#define PROG_SET_FEATURE		BIT(10)
> +
> +#define ONFI_STATUS_FAIL		BIT(0)
> +#define ONFI_STATUS_READY		BIT(6)
> +
> +#define PG_ADDR_SHIFT			16
> +#define BCH_MODE_SHIFT			25
> +#define BCH_EN_SHIFT			27
> +#define ECC_SIZE_SHIFT			16
> +
> +#define MEM_ADDR_MASK			GENMASK(7, 0)
> +#define BCH_MODE_MASK			GENMASK(27, 25)
> +
> +#define CS_MASK				GENMASK(31, 30)
> +#define CS_SHIFT			30
> +
> +#define PAGE_ERR_CNT_MASK		GENMASK(16, 8)
> +#define PKT_ERR_CNT_MASK		GENMASK(7, 0)
> +
> +#define NVDDR_MODE			BIT(9)
> +#define NVDDR_TIMING_MODE_SHIFT		3
> +
> +#define ONFI_ID_LEN			8
> +#define TEMP_BUF_SIZE			512
> +#define NVDDR_MODE_PACKET_SIZE		8
> +#define SDR_MODE_PACKET_SIZE		4
> +
> +#define ONFI_DATA_INTERFACE_NVDDR      (1 << 4)

BIT() ?


[...]

> +struct anfc {
> +	struct nand_hw_control controller;
> +	struct list_head chips;
> +	struct device *dev;
> +	void __iomem *base;
> +	int curr_cmd;
> +	struct clk *clk_sys;
> +	struct clk *clk_flash;
> +	bool dma;
> +	bool err;
> +	bool iswriteoob;
> +	u8 buf[TEMP_BUF_SIZE];
> +	int irq;
> +	u32 bufshift;
> +	int csnum;
> +	struct completion evnt;

event ?

> +};

[...]

> +static void anfc_prepare_cmd(struct anfc *nfc, u8 cmd1, u8 cmd2, u8 dmamode,
> +			     u32 pagesize, u8 addrcycles)
> +{
> +	u32 regval;
> +
> +	regval = cmd1 | (cmd2 << CMD2_SHIFT);
> +	if (dmamode && nfc->dma)
> +		regval |= DMA_ENABLE << DMA_EN_SHIFT;
> +	if (addrcycles)
> +		regval |= addrcycles << ADDR_CYCLES_SHIFT;
> +	if (pagesize)
> +		regval |= anfc_page(pagesize) << REG_PAGE_SIZE_SHIFT;

Drop the if (foo), if it's zero, the regval would be OR'd with zero.

> +	writel(regval, nfc->base + CMD_OFST);
> +}
> +
> +static int anfc_write_oob(struct mtd_info *mtd, struct nand_chip *chip,
> +			  int page)
> +{
> +	struct anfc *nfc = to_anfc(chip->controller);
> +
> +	nfc->iswriteoob = true;
> +	chip->cmdfunc(mtd, NAND_CMD_SEQIN, mtd->writesize, page);
> +	chip->write_buf(mtd, chip->oob_poi, mtd->oobsize);
> +	nfc->iswriteoob = false;
> +
> +	return 0;
> +}
> +
> +static void anfc_read_buf(struct mtd_info *mtd, uint8_t *buf, int len)
> +{
> +	u32 pktcount, pktsize, eccintr = 0;
> +	unsigned int buf_rd_cnt = 0;
> +	u32 *bufptr = (u32 *)buf;
> +	struct nand_chip *chip = mtd_to_nand(mtd);
> +	struct anfc_nand_chip *achip = to_anfc_nand(chip);
> +	struct anfc *nfc = to_anfc(chip->controller);
> +	dma_addr_t paddr;
> +
> +	if (nfc->curr_cmd == NAND_CMD_READ0) {
> +		pktsize = achip->pktsize;
> +		pktcount = DIV_ROUND_UP(mtd->writesize, pktsize);
> +		if (!achip->bch)
> +			eccintr = MBIT_ERROR;
> +	} else {
> +		pktsize = len;
> +		pktcount = 1;
> +	}
> +
> +	anfc_setpktszcnt(nfc, pktsize, pktcount);
> +
> +	if (nfc->dma) {
> +		paddr = dma_map_single(nfc->dev, buf, len, DMA_FROM_DEVICE);
> +		if (dma_mapping_error(nfc->dev, paddr)) {
> +			dev_err(nfc->dev, "Read buffer mapping error");
> +			return;
> +		}
> +		lo_hi_writeq(paddr, nfc->base + DMA_ADDR0_OFST);
> +		anfc_enable_intrs(nfc, (XFER_COMPLETE | eccintr));
> +		writel(PROG_PGRD, nfc->base + PROG_OFST);
> +		anfc_wait_for_event(nfc);
> +		dma_unmap_single(nfc->dev, paddr, len, DMA_FROM_DEVICE);

Split this function into anfc_read_buf() and then anfc_read_buf_pio()
and anfc_read_buf_dma() to avoid this ugliness. Also, does this handle
any errors in any way ? Looks like it ignores all errors, so please fix.

> +		return;
> +	}
> +
> +	anfc_enable_intrs(nfc, (READ_READY | eccintr));
> +	writel(PROG_PGRD, nfc->base + PROG_OFST);
> +
> +	while (buf_rd_cnt < pktcount) {
> +		anfc_wait_for_event(nfc);
> +		buf_rd_cnt++;
> +
> +		if (buf_rd_cnt == pktcount)
> +			anfc_enable_intrs(nfc, XFER_COMPLETE);
> +
> +		readsl(nfc->base + DATA_PORT_OFST, bufptr, pktsize/4);
> +		bufptr += (pktsize / 4);
> +
> +		if (buf_rd_cnt < pktcount)
> +			anfc_enable_intrs(nfc, (READ_READY | eccintr));
> +	}
> +
> +	anfc_wait_for_event(nfc);
> +}
> +
> +static void anfc_write_buf(struct mtd_info *mtd, const uint8_t *buf, int len)
> +{
> +	u32 pktcount, pktsize;
> +	unsigned int buf_wr_cnt = 0;
> +	u32 *bufptr = (u32 *)buf;
> +	struct nand_chip *chip = mtd_to_nand(mtd);
> +	struct anfc_nand_chip *achip = to_anfc_nand(chip);
> +	struct anfc *nfc = to_anfc(chip->controller);
> +	dma_addr_t paddr;
> +
> +	if (nfc->iswriteoob) {
> +		pktsize = len;
> +		pktcount = 1;
> +	} else {
> +		pktsize = achip->pktsize;
> +		pktcount = mtd->writesize / pktsize;
> +	}

This looks like a copy of the read path. Can these two functions be
parametrized and merged ?

> +	anfc_setpktszcnt(nfc, pktsize, pktcount);
> +
> +	if (nfc->dma) {
> +		paddr = dma_map_single(nfc->dev, (void *)buf, len,
> +				       DMA_TO_DEVICE);
> +		if (dma_mapping_error(nfc->dev, paddr)) {
> +			dev_err(nfc->dev, "Write buffer mapping error");
> +			return;
> +		}
> +		lo_hi_writeq(paddr, nfc->base + DMA_ADDR0_OFST);
> +		anfc_enable_intrs(nfc, XFER_COMPLETE);
> +		writel(PROG_PGPROG, nfc->base + PROG_OFST);
> +		anfc_wait_for_event(nfc);
> +		dma_unmap_single(nfc->dev, paddr, len, DMA_TO_DEVICE);
> +		return;
> +	}
> +
> +	anfc_enable_intrs(nfc, WRITE_READY);
> +	writel(PROG_PGPROG, nfc->base + PROG_OFST);
> +
> +	while (buf_wr_cnt < pktcount) {
> +		anfc_wait_for_event(nfc);
> +		buf_wr_cnt++;
> +		if (buf_wr_cnt == pktcount)
> +			anfc_enable_intrs(nfc, XFER_COMPLETE);
> +
> +		writesl(nfc->base + DATA_PORT_OFST, bufptr, pktsize/4);
> +		bufptr += (pktsize / 4);
> +
> +		if (buf_wr_cnt < pktcount)
> +			anfc_enable_intrs(nfc, WRITE_READY);
> +	}
> +
> +	anfc_wait_for_event(nfc);
> +}


[...]

> +static void anfc_writefifo(struct anfc *nfc, u32 prog, u32 size, u8 *buf)
> +{
> +	u32 *bufptr = (u32 *)buf;
> +
> +	anfc_enable_intrs(nfc, WRITE_READY);
> +
> +	writel(prog, nfc->base + PROG_OFST);
> +	anfc_wait_for_event(nfc);
> +
> +	anfc_enable_intrs(nfc, XFER_COMPLETE);
> +	writesl(nfc->base + DATA_PORT_OFST, bufptr, size/4);

use ioread32_rep and iowrite32_rep , otherwise this won't compile on x86
with COMPILE_TEST.

> +	anfc_wait_for_event(nfc);
> +}
> +
> +static void anfc_readfifo(struct anfc *nfc, u32 prog, u32 size)
> +{
> +	u32 *bufptr = (u32 *)nfc->buf;
> +
> +	anfc_enable_intrs(nfc, READ_READY);
> +
> +	writel(prog, nfc->base + PROG_OFST);
> +	anfc_wait_for_event(nfc);
> +
> +	anfc_enable_intrs(nfc, XFER_COMPLETE);
> +	readsl(nfc->base + DATA_PORT_OFST, bufptr, size/4);

See above

> +	anfc_wait_for_event(nfc);
> +}


[...]

> +static void anfc_select_chip(struct mtd_info *mtd, int num)
> +{
> +	u32 val;
> +	struct nand_chip *chip = mtd_to_nand(mtd);
> +	struct anfc_nand_chip *achip = to_anfc_nand(chip);
> +	struct anfc *nfc = to_anfc(chip->controller);
> +
> +	if (num == -1)
> +		return;
> +
> +	val = readl(nfc->base + MEM_ADDR2_OFST);
> +	val = (val & ~(CS_MASK)) | (achip->csnum << CS_SHIFT);
> +	val = (val & ~(BCH_MODE_MASK)) | (achip->bchmode << BCH_MODE_SHIFT);

Just rewrite this as a series of val &= ~(foo | bar); val |= baz | quux;
for clarity sake.

> +	writel(val, nfc->base + MEM_ADDR2_OFST);
> +	nfc->csnum = achip->csnum;
> +	writel(achip->eccval, nfc->base + ECC_OFST);
> +	writel(achip->inftimeval, nfc->base + DATA_INTERFACE_REG);
> +}
> +
> +static irqreturn_t anfc_irq_handler(int irq, void *ptr)
> +{
> +	struct anfc *nfc = ptr;
> +	u32 regval = 0, status;
> +
> +	status = readl(nfc->base + INTR_STS_OFST);
> +	if (status & XFER_COMPLETE) {
> +		complete(&nfc->evnt);
> +		regval |= XFER_COMPLETE;

Can the complete() be invoked multiple times ? That seems a bit odd.

> +	}
> +
> +	if (status & READ_READY) {
> +		complete(&nfc->evnt);
> +		regval |= READ_READY;
> +	}
> +
> +	if (status & WRITE_READY) {
> +		complete(&nfc->evnt);
> +		regval |= WRITE_READY;
> +	}
> +
> +	if (status & MBIT_ERROR) {
> +		nfc->err = true;
> +		complete(&nfc->evnt);
> +		regval |= MBIT_ERROR;
> +	}
> +
> +	if (regval) {
> +		writel(regval, nfc->base + INTR_STS_OFST);
> +		writel(0, nfc->base + INTR_STS_EN_OFST);
> +		writel(0, nfc->base + INTR_SIG_EN_OFST);
> +
> +		return IRQ_HANDLED;
> +	}
> +
> +	return IRQ_NONE;
> +}
> +
> +static int anfc_onfi_set_features(struct mtd_info *mtd, struct nand_chip *chip,
> +				int addr, uint8_t *subfeature_param)
> +{
> +	struct anfc *nfc = to_anfc(chip->controller);
> +	struct anfc_nand_chip *achip = to_anfc_nand(chip);
> +	int status;
> +
> +	if (!chip->onfi_version || !(le16_to_cpu(chip->onfi_params.opt_cmd)
> +		& ONFI_OPT_CMD_SET_GET_FEATURES))

Split this into two conditions to improve readability.

> +		return -EINVAL;
> +
> +	chip->cmdfunc(mtd, NAND_CMD_SET_FEATURES, addr, -1);
> +	anfc_writefifo(nfc, PROG_SET_FEATURE, achip->spktsize,
> +			subfeature_param);
> +
> +	status = chip->waitfunc(mtd, chip);
> +	if (status & NAND_STATUS_FAIL)
> +		return -EIO;
> +
> +	return 0;
> +}
> +
> +static int anfc_init_timing_mode(struct anfc *nfc,
> +				 struct anfc_nand_chip *achip)
> +{
> +	int mode, err;
> +	unsigned int feature[2];
> +	u32 inftimeval;
> +	struct nand_chip *chip = &achip->chip;
> +	struct mtd_info *mtd = nand_to_mtd(chip);
> +
> +	memset(feature, 0, NVDDR_MODE_PACKET_SIZE);
> +	/* Get nvddr timing modes */
> +	mode = onfi_get_sync_timing_mode(chip) & 0xff;
> +	if (!mode) {
> +		mode = fls(onfi_get_async_timing_mode(chip)) - 1;
> +		inftimeval = mode;
> +	} else {
> +		mode = fls(mode) - 1;
> +		inftimeval = NVDDR_MODE | (mode << NVDDR_TIMING_MODE_SHIFT);
> +		mode |= ONFI_DATA_INTERFACE_NVDDR;
> +	}
> +
> +	feature[0] = mode;
> +	chip->select_chip(mtd, achip->csnum);
> +	err = chip->onfi_set_features(mtd, chip, ONFI_FEATURE_ADDR_TIMING_MODE,
> +				      (uint8_t *)feature);
> +	chip->select_chip(mtd, -1);
> +	if (err)
> +		return err;
> +
> +	achip->inftimeval = inftimeval;
> +
> +	if (mode & ONFI_DATA_INTERFACE_NVDDR)
> +		achip->spktsize = NVDDR_MODE_PACKET_SIZE;
> +
> +	return 0;
> +}

[...]

> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Xilinx, Inc");

There should be a contact with email address here.

> +MODULE_DESCRIPTION("Arasan NAND Flash Controller Driver");
> 


-- 
Best regards,
Marek Vasut

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