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Re: [PATCH v4 3/3] mtd: nand: jz4780: driver for NAND devices on JZ4780 SoCs

Started by	Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
First post	2015-09-06 23:30 +0200
Last post	2015-09-07 17:00 +0200
Articles	2 — 2 participants

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  Re: [PATCH v4 3/3] mtd: nand: jz4780: driver for NAND devices on  JZ4780 SoCs Ezequiel Garcia <ezequiel@vanguardiasur.com.ar> - 2015-09-06 23:30 +0200
    Re: [PATCH v4 3/3] mtd: nand: jz4780: driver for NAND devices on  JZ4780 SoCs Alex Smith <alex.smith@imgtec.com> - 2015-09-07 17:00 +0200

#1219864 — Re: [PATCH v4 3/3] mtd: nand: jz4780: driver for NAND devices on JZ4780 SoCs

From	Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Date	2015-09-06 23:30 +0200
Subject	Re: [PATCH v4 3/3] mtd: nand: jz4780: driver for NAND devices on JZ4780 SoCs
Message-ID	<q5PFE-2ev-7@gated-at.bofh.it>

On 27 Jul 03:21 PM, Alex Smith wrote:
> Add a driver for NAND devices connected to the NEMC on JZ4780 SoCs, as
> well as the hardware BCH controller. DMA is not currently implemented.
> 
> While older 47xx SoCs also have a BCH controller, they are incompatible
> with the one in the 4780 due to differing register/bit positions, which
> would make implementing a common driver for them quite messy.
> 

If the difference is only in register/bit positions, a common driver
might be fairly simple. See drivers/i2c/busses/i2c-mv64xxx.c,
which supports two different register layouts.

Anyway, the drivers look mostly good. Just a handful of comments.

> Signed-off-by: Alex Smith <alex.smith@imgtec.com>
> Cc: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@imgtec.com>
> Cc: David Woodhouse <dwmw2@infradead.org>
> Cc: Brian Norris <computersforpeace@gmail.com>
> Cc: linux-mtd@lists.infradead.org
> Cc: linux-kernel@vger.kernel.org
> ---
> v3 -> v4:
>  - Rebase to 4.2-rc4
>  - Change ECC_HW_OOB_FIRST to ECC_HW, reading OOB first is not necessary.
>  - Fix argument to get_device() in jz4780_bch_get()
> 
> v2 -> v3:
>  - Rebase to 4.0-rc6
>  - Reflect binding changes
>  - get/put_device in bch get/release
>  - Removed empty .remove() callback
>  - Removed .owner
>  - Set mtd->dev.parent
> 
> v1 -> v2:
>  - Fixed module license macro
>  - Rebase to 4.0-rc3
> ---
>  drivers/mtd/nand/Kconfig       |   7 +
>  drivers/mtd/nand/Makefile      |   1 +
>  drivers/mtd/nand/jz4780_bch.c  | 354 ++++++++++++++++++++++++++++++++++++++
>  drivers/mtd/nand/jz4780_bch.h  |  42 +++++
>  drivers/mtd/nand/jz4780_nand.c | 376 +++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 780 insertions(+)
>  create mode 100644 drivers/mtd/nand/jz4780_bch.c
>  create mode 100644 drivers/mtd/nand/jz4780_bch.h
>  create mode 100644 drivers/mtd/nand/jz4780_nand.c
> 
> diff --git a/drivers/mtd/nand/Kconfig b/drivers/mtd/nand/Kconfig
> index 5b2806a7e5f7..3900e5f93146 100644
> --- a/drivers/mtd/nand/Kconfig
> +++ b/drivers/mtd/nand/Kconfig
> @@ -511,6 +511,13 @@ config MTD_NAND_JZ4740
>  	help
>  		Enables support for NAND Flash on JZ4740 SoC based boards.
>  
> +config MTD_NAND_JZ4780
> +	tristate "Support for NAND on JZ4780 SoC"
> +	depends on MACH_JZ4780 && JZ4780_NEMC
> +	help
> +	  Enables support for NAND Flash connected to the NEMC on JZ4780 SoC
> +	  based boards, using the BCH controller for hardware error correction.
> +
>  config MTD_NAND_FSMC
>  	tristate "Support for NAND on ST Micros FSMC"
>  	depends on PLAT_SPEAR || ARCH_NOMADIK || ARCH_U8500 || MACH_U300
> diff --git a/drivers/mtd/nand/Makefile b/drivers/mtd/nand/Makefile
> index 1f897ec3c242..3ee2fd6bc641 100644
> --- a/drivers/mtd/nand/Makefile
> +++ b/drivers/mtd/nand/Makefile
> @@ -47,6 +47,7 @@ obj-$(CONFIG_MTD_NAND_NUC900)		+= nuc900_nand.o
>  obj-$(CONFIG_MTD_NAND_MPC5121_NFC)	+= mpc5121_nfc.o
>  obj-$(CONFIG_MTD_NAND_RICOH)		+= r852.o
>  obj-$(CONFIG_MTD_NAND_JZ4740)		+= jz4740_nand.o
> +obj-$(CONFIG_MTD_NAND_JZ4780)		+= jz4780_nand.o jz4780_bch.o
>  obj-$(CONFIG_MTD_NAND_GPMI_NAND)	+= gpmi-nand/
>  obj-$(CONFIG_MTD_NAND_XWAY)		+= xway_nand.o
>  obj-$(CONFIG_MTD_NAND_BCM47XXNFLASH)	+= bcm47xxnflash/
> diff --git a/drivers/mtd/nand/jz4780_bch.c b/drivers/mtd/nand/jz4780_bch.c
> new file mode 100644
> index 000000000000..1686d76f8457
> --- /dev/null
> +++ b/drivers/mtd/nand/jz4780_bch.c
> @@ -0,0 +1,354 @@
> +/*
> + * JZ4780 BCH controller
> + *
> + * Copyright (c) 2015 Imagination Technologies
> + * Author: Alex Smith <alex.smith@imgtec.com>
> + *
> + * 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.
> + */
> +
> +#include <linux/clk.h>
> +#include <linux/delay.h>
> +#include <linux/init.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/sched.h>
> +#include <linux/slab.h>
> +
> +#include "jz4780_bch.h"
> +
> +#define BCH_BHCR			0x0
> +#define BCH_BHCCR			0x8
> +#define BCH_BHCNT			0xc
> +#define BCH_BHDR			0x10
> +#define BCH_BHPAR0			0x14
> +#define BCH_BHERR0			0x84
> +#define BCH_BHINT			0x184
> +#define BCH_BHINTES			0x188
> +#define BCH_BHINTEC			0x18c
> +#define BCH_BHINTE			0x190
> +
> +#define BCH_BHCR_BSEL_SHIFT		4
> +#define BCH_BHCR_BSEL_MASK		(0x7f << BCH_BHCR_BSEL_SHIFT)
> +#define BCH_BHCR_ENCE			BIT(2)
> +#define BCH_BHCR_INIT			BIT(1)
> +#define BCH_BHCR_BCHE			BIT(0)
> +
> +#define BCH_BHCNT_PARITYSIZE_SHIFT	16
> +#define BCH_BHCNT_PARITYSIZE_MASK	(0x7f << BCH_BHCNT_PARITYSIZE_SHIFT)
> +#define BCH_BHCNT_BLOCKSIZE_SHIFT	0
> +#define BCH_BHCNT_BLOCKSIZE_MASK	(0x7ff << BCH_BHCNT_BLOCKSIZE_SHIFT)
> +
> +#define BCH_BHERR_MASK_SHIFT		16
> +#define BCH_BHERR_MASK_MASK		(0xffff << BCH_BHERR_MASK_SHIFT)
> +#define BCH_BHERR_INDEX_SHIFT		0
> +#define BCH_BHERR_INDEX_MASK		(0x7ff << BCH_BHERR_INDEX_SHIFT)
> +
> +#define BCH_BHINT_ERRC_SHIFT		24
> +#define BCH_BHINT_ERRC_MASK		(0x7f << BCH_BHINT_ERRC_SHIFT)
> +#define BCH_BHINT_TERRC_SHIFT		16
> +#define BCH_BHINT_TERRC_MASK		(0x7f << BCH_BHINT_TERRC_SHIFT)
> +#define BCH_BHINT_DECF			BIT(3)
> +#define BCH_BHINT_ENCF			BIT(2)
> +#define BCH_BHINT_UNCOR			BIT(1)
> +#define BCH_BHINT_ERR			BIT(0)
> +
> +#define BCH_CLK_RATE			(200 * 1000 * 1000)
> +
> +/* Timeout for BCH calculation/correction in milliseconds. */
> +#define BCH_TIMEOUT			100
> +
> +struct jz4780_bch {
> +	void __iomem *base;
> +	struct clk *clk;
> +};
> +
> +static void jz4780_bch_init(struct jz4780_bch *bch,
> +			    struct jz4780_bch_params *params, bool encode)
> +{
> +	uint32_t reg;
> +
> +	/* Clear interrupt status. */
> +	writel(readl(bch->base + BCH_BHINT), bch->base + BCH_BHINT);
> +
> +	/* Set up BCH count register. */
> +	reg = params->size << BCH_BHCNT_BLOCKSIZE_SHIFT;
> +	reg |= params->bytes << BCH_BHCNT_PARITYSIZE_SHIFT;
> +	writel(reg, bch->base + BCH_BHCNT);
> +
> +	/* Initialise and enable BCH. */
> +	reg = BCH_BHCR_BCHE | BCH_BHCR_INIT;
> +	reg |= params->strength << BCH_BHCR_BSEL_SHIFT;
> +	if (encode)
> +		reg |= BCH_BHCR_ENCE;
> +	writel(reg, bch->base + BCH_BHCR);
> +}
> +
> +static void jz4780_bch_disable(struct jz4780_bch *bch)
> +{
> +	writel(readl(bch->base + BCH_BHINT), bch->base + BCH_BHINT);
> +	writel(BCH_BHCR_BCHE, bch->base + BCH_BHCCR);
> +}
> +
> +static void jz4780_bch_write_data(struct jz4780_bch *bch, const void *buf,
> +				  size_t size)
> +{
> +	size_t size32 = size / sizeof(uint32_t);
> +	size_t size8 = size & (sizeof(uint32_t) - 1);
> +	const uint32_t *src32;
> +	const uint8_t *src8;
> +
> +	src32 = (const uint32_t *)buf;
> +	while (size32--)
> +		writel(*src32++, bch->base + BCH_BHDR);
> +
> +	src8 = (const uint8_t *)src32;
> +	while (size8--)
> +		writeb(*src8++, bch->base + BCH_BHDR);
> +}
> +
> +static void jz4780_bch_read_parity(struct jz4780_bch *bch, void *buf,
> +				   size_t size)
> +{
> +	size_t size32 = size / sizeof(uint32_t);
> +	size_t size8 = size & (sizeof(uint32_t) - 1);
> +	uint32_t *dest32;
> +	uint8_t *dest8;
> +	uint32_t val, offset = 0;
> +
> +	dest32 = (uint32_t *)buf;
> +	while (size32--) {
> +		*dest32++ = readl(bch->base + BCH_BHPAR0 + offset);
> +		offset += sizeof(uint32_t);
> +	}
> +
> +	dest8 = (uint8_t *)dest32;
> +	val = readl(bch->base + BCH_BHPAR0 + offset);
> +	switch (size8) {
> +	case 3:
> +		dest8[2] = (val >> 16) & 0xff;
> +	case 2:
> +		dest8[1] = (val >> 8) & 0xff;
> +	case 1:
> +		dest8[0] = val & 0xff;
> +		break;
> +	}
> +}
> +
> +static bool jz4780_bch_wait_complete(struct jz4780_bch *bch, unsigned int irq,
> +				     uint32_t *status)
> +{
> +	unsigned long timeout = jiffies + msecs_to_jiffies(BCH_TIMEOUT);
> +	uint32_t reg;
> +
> +	/*
> +	 * While we could use use interrupts here and sleep until the operation
> +	 * completes, the controller works fairly quickly (usually a few
> +	 * microseconds), so the overhead of sleeping until we get an interrupt
> +	 * actually quite noticably decreases performance.

s/noticably/noticeably

> +	 */
> +	do {
> +		reg = readl(bch->base + BCH_BHINT);
> +		if ((reg & irq) == irq) {
> +			if (status)
> +				*status = reg;
> +
> +			writel(reg, bch->base + BCH_BHINT);
> +			return true;
> +		}
> +
> +		cond_resched();
> +	} while (time_before(jiffies, timeout));
> +

Maybe you can use some readl_poll_timeout variant (with null delay).

> +	return false;
> +}
> +
> +/**
> + * jz4780_bch_calculate() - calculate ECC for a data buffer
> + * @dev: BCH device.
> + * @params: BCH parameters.
> + * @buf: input buffer with raw data.
> + * @ecc_code: output buffer with ECC.
> + *
> + * Return: 0 on success, -ETIMEDOUT if timed out while waiting for BCH
> + * controller.
> + */
> +int jz4780_bch_calculate(struct device *dev, struct jz4780_bch_params *params,
> +			 const uint8_t *buf, uint8_t *ecc_code)
> +{
> +	struct jz4780_bch *bch = dev_get_drvdata(dev);
> +	int ret = 0;
> +
> +	jz4780_bch_init(bch, params, true);
> +	jz4780_bch_write_data(bch, buf, params->size);
> +
> +	if (jz4780_bch_wait_complete(bch, BCH_BHINT_ENCF, NULL)) {
> +		jz4780_bch_read_parity(bch, ecc_code, params->bytes);
> +	} else {
> +		dev_err(dev, "timed out while calculating ECC\n");
> +		ret = -ETIMEDOUT;
> +	}
> +
> +	jz4780_bch_disable(bch);
> +	return ret;
> +}
> +EXPORT_SYMBOL(jz4780_bch_calculate);
> +
> +/**
> + * jz4780_bch_correct() - detect and correct bit errors
> + * @dev: BCH device.
> + * @params: BCH parameters.
> + * @buf: raw data read from the chip.
> + * @ecc_code: ECC read from the chip.
> + *
> + * Given the raw data and the ECC read from the NAND device, detects and
> + * corrects errors in the data.
> + *
> + * Return: the number of bit errors corrected, or -1 if there are too many
> + * errors to correct or we timed out waiting for the controller.
> + */
> +int jz4780_bch_correct(struct device *dev, struct jz4780_bch_params *params,
> +		       uint8_t *buf, uint8_t *ecc_code)
> +{
> +	struct jz4780_bch *bch = dev_get_drvdata(dev);
> +	uint32_t reg, mask, index;
> +	int i, ret, count;
> +
> +	jz4780_bch_init(bch, params, false);
> +	jz4780_bch_write_data(bch, buf, params->size);
> +	jz4780_bch_write_data(bch, ecc_code, params->bytes);
> +
> +	if (!jz4780_bch_wait_complete(bch, BCH_BHINT_DECF, &reg)) {
> +		dev_err(dev, "timed out while correcting data\n");
> +		ret = -1;
> +		goto out;
> +	}
> +
> +	if (reg & BCH_BHINT_UNCOR) {
> +		dev_warn(dev, "uncorrectable ECC error\n");
> +		ret = -1;
> +		goto out;
> +	}
> +
> +	/* Correct any detected errors. */
> +	if (reg & BCH_BHINT_ERR) {
> +		count = (reg & BCH_BHINT_ERRC_MASK) >> BCH_BHINT_ERRC_SHIFT;
> +		ret = (reg & BCH_BHINT_TERRC_MASK) >> BCH_BHINT_TERRC_SHIFT;
> +
> +		for (i = 0; i < count; i++) {
> +			reg = readl(bch->base + BCH_BHERR0 + (i * 4));
> +			mask = (reg & BCH_BHERR_MASK_MASK) >>
> +						BCH_BHERR_MASK_SHIFT;
> +			index = (reg & BCH_BHERR_INDEX_MASK) >>
> +						BCH_BHERR_INDEX_SHIFT;
> +			buf[(index * 2) + 0] ^= mask;
> +			buf[(index * 2) + 1] ^= mask >> 8;
> +		}
> +	} else {
> +		ret = 0;
> +	}
> +
> +out:
> +	jz4780_bch_disable(bch);
> +	return ret;
> +}
> +EXPORT_SYMBOL(jz4780_bch_correct);
> +
> +/**
> + * jz4780_bch_get() - get the BCH controller device
> + * @np: BCH device tree node.
> + * @dev: where to store pointer to BCH controller device.
> + *
> + * Gets the BCH controller device from the specified device tree node. The
> + * device must be released with jz4780_bch_release() when it is no longer being
> + * used.
> + *
> + * Return: 0 on success, -EPROBE_DEFER if the controller has not yet been
> + * initialised.
> + */
> +int jz4780_bch_get(struct device_node *np, struct device **dev)
> +{
> +	struct platform_device *pdev;
> +	struct jz4780_bch *bch;
> +
> +	pdev = of_find_device_by_node(np);
> +	if (!pdev || !platform_get_drvdata(pdev))
> +		return -EPROBE_DEFER;
> +
> +	get_device(&pdev->dev);
> +
> +	bch = platform_get_drvdata(pdev);
> +	clk_prepare_enable(bch->clk);
> +
> +	*dev = &pdev->dev;
> +	return 0;
> +}
> +EXPORT_SYMBOL(jz4780_bch_get);
> +
> +/**
> + * jz4780_bch_release() - release the BCH controller device
> + * @dev: BCH device.
> + */
> +void jz4780_bch_release(struct device *dev)
> +{
> +	struct jz4780_bch *bch = dev_get_drvdata(dev);
> +
> +	clk_disable_unprepare(bch->clk);
> +	put_device(dev);
> +}
> +EXPORT_SYMBOL(jz4780_bch_release);
> +
> +static int jz4780_bch_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct jz4780_bch *bch;
> +	struct resource *res;
> +
> +	bch = devm_kzalloc(dev, sizeof(*bch), GFP_KERNEL);
> +	if (!bch)
> +		return -ENOMEM;
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	bch->base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(bch->base)) {
> +		dev_err(dev, "failed to get I/O memory\n");

This message is not needed. See lib/devres.c.

> +		return PTR_ERR(bch->base);
> +	}
> +
> +	jz4780_bch_disable(bch);
> +
> +	bch->clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(bch->clk)) {
> +		dev_err(dev, "failed to get clock: %ld\n", PTR_ERR(bch->clk));
> +		return PTR_ERR(bch->clk);
> +	}
> +
> +	clk_set_rate(bch->clk, BCH_CLK_RATE);
> +
> +	platform_set_drvdata(pdev, bch);
> +	dev_info(dev, "JZ4780 BCH initialised\n");

This message is not too useful.

> +	return 0;
> +}
> +
> +static const struct of_device_id jz4780_bch_dt_match[] = {
> +	{ .compatible = "ingenic,jz4780-bch" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, jz4780_bch_dt_match);
> +
> +static struct platform_driver jz4780_bch_driver = {
> +	.probe		= jz4780_bch_probe,

Why no remove?

> +	.driver	= {
> +		.name	= "jz4780-bch",
> +		.of_match_table = of_match_ptr(jz4780_bch_dt_match),
> +	},
> +};
> +module_platform_driver(jz4780_bch_driver);
> +
> +MODULE_AUTHOR("Alex Smith <alex.smith@imgtec.com>");
> +MODULE_DESCRIPTION("Ingenic JZ4780 BCH error correction driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/drivers/mtd/nand/jz4780_bch.h b/drivers/mtd/nand/jz4780_bch.h
> new file mode 100644
> index 000000000000..cf315f384b6e
> --- /dev/null
> +++ b/drivers/mtd/nand/jz4780_bch.h
> @@ -0,0 +1,42 @@
> +/*
> + * JZ4780 BCH controller
> + *
> + * Copyright (c) 2015 Imagination Technologies
> + * Author: Alex Smith <alex.smith@imgtec.com>
> + *
> + * 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.
> + */
> +
> +#ifndef __DRIVERS_MTD_NAND_JZ4780_BCH_H__
> +#define __DRIVERS_MTD_NAND_JZ4780_BCH_H__
> +
> +#include <linux/types.h>
> +
> +struct device;
> +struct device_node;
> +
> +/**
> + * struct jz4780_bch_params - BCH parameters
> + * @size: data bytes per ECC step.
> + * @bytes: ECC bytes per step.
> + * @strength: number of correctable bits per ECC step.
> + */
> +struct jz4780_bch_params {
> +	int size;
> +	int bytes;
> +	int strength;
> +};
> +
> +extern int jz4780_bch_calculate(struct device *dev,
> +				struct jz4780_bch_params *params,
> +				const uint8_t *buf, uint8_t *ecc_code);
> +extern int jz4780_bch_correct(struct device *dev,
> +			      struct jz4780_bch_params *params, uint8_t *buf,
> +			      uint8_t *ecc_code);
> +
> +extern int jz4780_bch_get(struct device_node *np, struct device **dev);
> +extern void jz4780_bch_release(struct device *dev);
> +
> +#endif /* __DRIVERS_MTD_NAND_JZ4780_BCH_H__ */
> diff --git a/drivers/mtd/nand/jz4780_nand.c b/drivers/mtd/nand/jz4780_nand.c
> new file mode 100644
> index 000000000000..925a6b65363a
> --- /dev/null
> +++ b/drivers/mtd/nand/jz4780_nand.c
> @@ -0,0 +1,376 @@
> +/*
> + * JZ4780 NAND driver
> + *
> + * Copyright (c) 2015 Imagination Technologies
> + * Author: Alex Smith <alex.smith@imgtec.com>
> + *
> + * 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.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_gpio.h>
> +#include <linux/of_mtd.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +
> +#include <linux/mtd/mtd.h>
> +#include <linux/mtd/nand.h>
> +#include <linux/mtd/partitions.h>
> +
> +#include <linux/jz4780-nemc.h>
> +
> +#include "jz4780_bch.h"
> +
> +#define OFFSET_DATA	0x00000000
> +#define OFFSET_CMD	0x00400000
> +#define OFFSET_ADDR	0x00800000
> +
> +/* Command delay when there is no R/B pin (in microseconds). */
> +#define RB_DELAY	50
> +
> +struct jz4780_nand_chip {
> +	unsigned int bank;
> +	void __iomem *base;
> +};
> +
> +struct jz4780_nand {
> +	struct mtd_info mtd;
> +	struct nand_chip chip;
> +
> +	struct device *dev;
> +	struct device *bch;
> +
> +	struct nand_ecclayout ecclayout;
> +
> +	int busy_gpio;
> +	int wp_gpio;
> +	unsigned int busy_gpio_active_low: 1;
> +	unsigned int wp_gpio_active_low: 1;
> +	unsigned int reading: 1;
> +
> +	unsigned int num_banks;
> +	int selected;
> +	struct jz4780_nand_chip chips[];
> +};
> +
> +static inline struct jz4780_nand *to_jz4780_nand(struct mtd_info *mtd)
> +{
> +	return container_of(mtd, struct jz4780_nand, mtd);
> +}
> +
> +static void jz4780_nand_select_chip(struct mtd_info *mtd, int chipnr)
> +{
> +	struct jz4780_nand *nand = to_jz4780_nand(mtd);
> +	struct jz4780_nand_chip *chip;
> +
> +	if (chipnr == -1) {
> +		/* Ensure the currently selected chip is deasserted. */
> +		if (nand->selected >= 0) {
> +			chip = &nand->chips[nand->selected];
> +			jz4780_nemc_assert(nand->dev, chip->bank, false);
> +		}
> +	} else {
> +		chip = &nand->chips[chipnr];
> +		nand->chip.IO_ADDR_R = chip->base + OFFSET_DATA;
> +		nand->chip.IO_ADDR_W = chip->base + OFFSET_DATA;
> +	}
> +
> +	nand->selected = chipnr;
> +}
> +
> +static void jz4780_nand_cmd_ctrl(struct mtd_info *mtd, int cmd,
> +				 unsigned int ctrl)
> +{
> +	struct jz4780_nand *nand = to_jz4780_nand(mtd);
> +	struct jz4780_nand_chip *chip;
> +
> +	BUG_ON(nand->selected < 0);

Maybe instead of BUG() you could use a WARN() and avoid
killing the kernel.

> +	chip = &nand->chips[nand->selected];
> +
> +	if (ctrl & NAND_CTRL_CHANGE) {
> +		if (ctrl & NAND_ALE)
> +			nand->chip.IO_ADDR_W = chip->base + OFFSET_ADDR;
> +		else if (ctrl & NAND_CLE)
> +			nand->chip.IO_ADDR_W = chip->base + OFFSET_CMD;
> +		else
> +			nand->chip.IO_ADDR_W = chip->base + OFFSET_DATA;
> +
> +		jz4780_nemc_assert(nand->dev, chip->bank, ctrl & NAND_NCE);
> +	}
> +
> +	if (cmd != NAND_CMD_NONE)
> +		writeb(cmd, nand->chip.IO_ADDR_W);
> +}
> +
> +static int jz4780_nand_dev_ready(struct mtd_info *mtd)
> +{
> +	struct jz4780_nand *nand = to_jz4780_nand(mtd);
> +
> +	return !(gpio_get_value(nand->busy_gpio) ^ nand->busy_gpio_active_low);
> +}
> +
> +static void jz4780_nand_ecc_hwctl(struct mtd_info *mtd, int mode)
> +{
> +	struct jz4780_nand *nand = to_jz4780_nand(mtd);
> +
> +	nand->reading = (mode == NAND_ECC_READ);
> +}
> +
> +static int jz4780_nand_ecc_calculate(struct mtd_info *mtd, const uint8_t *dat,
> +				     uint8_t *ecc_code)
> +{
> +	struct jz4780_nand *nand = to_jz4780_nand(mtd);
> +	struct jz4780_bch_params params;
> +
> +	/*
> +	 * Don't need to generate the ECC when reading, BCH does it for us as
> +	 * part of decoding/correction.
> +	 */
> +	if (nand->reading)
> +		return 0;
> +
> +	params.size = nand->chip.ecc.size;
> +	params.bytes = nand->chip.ecc.bytes;
> +	params.strength = nand->chip.ecc.strength;
> +
> +	return jz4780_bch_calculate(nand->bch, &params, dat, ecc_code);
> +}
> +
> +static int jz4780_nand_ecc_correct(struct mtd_info *mtd, uint8_t *dat,
> +				   uint8_t *read_ecc, uint8_t *calc_ecc)
> +{
> +	struct jz4780_nand *nand = to_jz4780_nand(mtd);
> +	struct jz4780_bch_params params;
> +
> +	params.size = nand->chip.ecc.size;
> +	params.bytes = nand->chip.ecc.bytes;
> +	params.strength = nand->chip.ecc.strength;
> +
> +	return jz4780_bch_correct(nand->bch, &params, dat, read_ecc);
> +}
> +
> +static void jz4780_nand_init_ecc(struct jz4780_nand *nand, struct device *dev)
> +{
> +	struct mtd_info *mtd = &nand->mtd;
> +	struct nand_chip *chip = &nand->chip;
> +	struct nand_ecclayout *layout = &nand->ecclayout;
> +	uint32_t start, i;
> +
> +	chip->ecc.size = of_get_nand_ecc_step_size(dev->of_node);
> +	if (chip->ecc.size < 0)
> +		chip->ecc.size = 1024;
> +
> +	chip->ecc.strength = of_get_nand_ecc_strength(dev->of_node);
> +	if (chip->ecc.strength < 0)
> +		chip->ecc.strength = 24;
> +
> +	chip->ecc.bytes = fls(1 + 8 * chip->ecc.size) * chip->ecc.strength / 8;
> +
> +	dev_info(dev, "using %s BCH (strength %d, size %d, bytes %d)\n",
> +		 (nand->bch) ? "hardware" : "software", chip->ecc.strength,
> +		 chip->ecc.size, chip->ecc.bytes);
> +
> +	if (nand->bch) {
> +		chip->ecc.mode = NAND_ECC_HW;
> +		chip->ecc.hwctl = jz4780_nand_ecc_hwctl;
> +		chip->ecc.calculate = jz4780_nand_ecc_calculate;
> +		chip->ecc.correct = jz4780_nand_ecc_correct;
> +	} else {
> +		chip->ecc.mode = NAND_ECC_SOFT_BCH;
> +	}
> +
> +	/* Generate ECC layout. ECC codes are right aligned in the OOB area. */
> +	layout->eccbytes = mtd->writesize / chip->ecc.size * chip->ecc.bytes;
> +	start = mtd->oobsize - layout->eccbytes;
> +	for (i = 0; i < layout->eccbytes; i++)
> +		layout->eccpos[i] = start + i;
> +
> +	layout->oobfree[0].offset = 2;
> +	layout->oobfree[0].length = mtd->oobsize - layout->eccbytes - 2;
> +
> +	chip->ecc.layout = layout;
> +}
> +
> +static int jz4780_nand_init_chips(struct jz4780_nand *nand, struct device *dev)
> +{
> +	struct jz4780_nand_chip *chip;
> +	const __be32 *prop;
> +	u64 addr, size;
> +	int i = 0;
> +
> +	/*
> +	 * Iterate over each bank assigned to this device and request resources.
> +	 * The bank numbers may not be consecutive, but nand_scan_ident()
> +	 * expects chip numbers to be, so fill out a consecutive array of chips
> +	 * which map chip number to actual bank number.
> +	 */
> +	while ((prop = of_get_address(dev->of_node, i, &size, NULL))) {
> +		chip = &nand->chips[i];
> +		chip->bank = of_read_number(prop, 1);
> +
> +		jz4780_nemc_set_type(nand->dev, chip->bank,
> +				     JZ4780_NEMC_BANK_NAND);
> +
> +		addr = of_translate_address(dev->of_node, prop);

Are you sure you must translate the address yourself?
Isn't this handled by the OF magic behing the ranges property
in the NEMC DT node?

> +		if (addr == OF_BAD_ADDR)
> +			return -EINVAL;
> +
> +		chip->base = devm_ioremap(dev, addr, size);
> +		if (IS_ERR(chip->base)) {
> +			dev_err(dev, "failed to map bank %u: %ld\n", chip->bank,
> +				PTR_ERR(chip->base));
> +			return PTR_ERR(chip->base);
> +		}
> +
> +		i++;
> +	}
> +
> +	return 0;
> +}
> +
> +static int jz4780_nand_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	unsigned int num_banks;
> +	struct jz4780_nand *nand;
> +	struct device_node *bch_np;
> +	struct mtd_info *mtd;
> +	struct nand_chip *chip;
> +	enum of_gpio_flags flags;
> +	struct mtd_part_parser_data ppdata;
> +	int ret;
> +
> +	num_banks = jz4780_nemc_num_banks(dev);
> +
> +	nand = devm_kzalloc(dev,
> +			sizeof(*nand) + (sizeof(nand->chips[0]) * num_banks),
> +			GFP_KERNEL);
> +	if (!nand)
> +		return -ENOMEM;
> +
> +	nand->dev = dev;
> +	nand->num_banks = num_banks;
> +	nand->selected = -1;
> +
> +	/* Look for the BCH controller. */
> +	bch_np = of_parse_phandle(dev->of_node, "ingenic,bch-device", 0);
> +	if (bch_np) {
> +		ret = jz4780_bch_get(bch_np, &nand->bch);
> +		of_node_put(bch_np);
> +		if (ret)
> +			return ret;
> +	}
> +
> +	mtd = &nand->mtd;
> +	chip = &nand->chip;
> +	mtd->priv = chip;
> +	mtd->owner = THIS_MODULE;
> +	mtd->name = "jz4780-nand";

Nit: you might want to use a macro and avoid duplicating
the name string.

> +	mtd->dev.parent = dev;
> +
> +	chip->chip_delay = RB_DELAY;
> +	chip->options = NAND_NO_SUBPAGE_WRITE;
> +	chip->bbt_options = NAND_BBT_USE_FLASH;
> +	chip->select_chip = jz4780_nand_select_chip;
> +	chip->cmd_ctrl = jz4780_nand_cmd_ctrl;
> +
> +	nand->busy_gpio = of_get_named_gpio_flags(dev->of_node,
> +						  "rb-gpios",
> +						  0, &flags);
> +	if (gpio_is_valid(nand->busy_gpio)) {
> +		ret = devm_gpio_request(dev, nand->busy_gpio, "NAND busy");
> +		if (ret) {
> +			dev_err(dev, "failed to request busy GPIO %d: %d\n",
> +				nand->busy_gpio, ret);
> +			goto err_release_bch;
> +		}
> +
> +		nand->busy_gpio_active_low = flags & OF_GPIO_ACTIVE_LOW;
> +		gpio_direction_input(nand->busy_gpio);
> +
> +		chip->dev_ready = jz4780_nand_dev_ready;
> +	}
> +
> +	nand->wp_gpio = of_get_named_gpio_flags(dev->of_node, "wp-gpios",
> +						0, &flags);
> +	if (gpio_is_valid(nand->wp_gpio)) {
> +		ret = devm_gpio_request(dev, nand->wp_gpio, "NAND WP");
> +		if (ret) {
> +			dev_err(dev, "failed to request WP GPIO %d: %d\n",
> +				nand->wp_gpio, ret);
> +			goto err_release_bch;
> +		}
> +
> +		nand->wp_gpio_active_low = flags & OF_GPIO_ACTIVE_LOW;
> +		gpio_direction_output(nand->wp_gpio, nand->wp_gpio_active_low);
> +	}
> +
> +	ret = jz4780_nand_init_chips(nand, dev);
> +	if (ret)
> +		goto err_release_bch;
> +
> +	ret = nand_scan_ident(mtd, num_banks, NULL);
> +	if (ret)
> +		goto err_release_bch;
> +
> +	jz4780_nand_init_ecc(nand, dev);
> +
> +	ret = nand_scan_tail(mtd);
> +	if (ret)
> +		goto err_release_bch;
> +
> +	ppdata.of_node = dev->of_node;
> +	ret = mtd_device_parse_register(mtd, NULL, &ppdata, NULL, 0);
> +	if (ret)
> +		goto err_release_nand;
> +
> +	platform_set_drvdata(pdev, nand);
> +	dev_info(dev, "JZ4780 NAND initialised\n");

Ditto.

> +	return 0;
> +
> +err_release_nand:
> +	nand_release(mtd);
> +
> +err_release_bch:
> +	if (nand->bch)
> +		jz4780_bch_release(nand->bch);
> +
> +	return ret;
> +}
> +
> +static int jz4780_nand_remove(struct platform_device *pdev)
> +{
> +	struct jz4780_nand *nand = platform_get_drvdata(pdev);
> +
> +	if (nand->bch)
> +		jz4780_bch_release(nand->bch);
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id jz4780_nand_dt_match[] = {
> +	{ .compatible = "ingenic,jz4780-nand" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, jz4780_nand_dt_match);
> +
> +static struct platform_driver jz4780_nand_driver = {
> +	.probe		= jz4780_nand_probe,
> +	.remove		= jz4780_nand_remove,
> +	.driver	= {
> +		.name	= "jz4780-nand",
> +		.of_match_table = of_match_ptr(jz4780_nand_dt_match),
> +	},
> +};
> +module_platform_driver(jz4780_nand_driver);
> +
> +MODULE_AUTHOR("Alex Smith <alex.smith@imgtec.com>");
> +MODULE_DESCRIPTION("Ingenic JZ4780 NAND driver");
> +MODULE_LICENSE("GPL v2");
> -- 
> 2.4.6
> 
> 
> ______________________________________________________
> Linux MTD discussion mailing list
> http://lists.infradead.org/mailman/listinfo/linux-mtd/

-- 
Ezequiel Garcia, VanguardiaSur
www.vanguardiasur.com.ar
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#1220259

From	Alex Smith <alex.smith@imgtec.com>
Date	2015-09-07 17:00 +0200
Message-ID	<q663M-fz-29@gated-at.bofh.it>
In reply to	#1219864

Hi,

On 06/09/2015 22:21, Ezequiel Garcia wrote:
> On 27 Jul 03:21 PM, Alex Smith wrote:
>> Add a driver for NAND devices connected to the NEMC on JZ4780 SoCs, as
>> well as the hardware BCH controller. DMA is not currently implemented.
>>
>> While older 47xx SoCs also have a BCH controller, they are incompatible
>> with the one in the 4780 due to differing register/bit positions, which
>> would make implementing a common driver for them quite messy.
>>
> 
> If the difference is only in register/bit positions, a common driver
> might be fairly simple. See drivers/i2c/busses/i2c-mv64xxx.c,
> which supports two different register layouts.

I've just gone back and looked at the older SoCs and it doesn't seem as though this commit message really applies to the JZ4740, which is the only other Ingenic SoC currently supported upstream. The 4740 doesn't have a BCH controller at all and the NAND interface is fairly different. I think this driver could potentially be reused if support for the JZ4770 makes it upstream, for now though a separate driver is certainly needed for the 4780.


>> +	return 0;
>> +}
>> +
>> +static const struct of_device_id jz4780_bch_dt_match[] = {
>> +	{ .compatible = "ingenic,jz4780-bch" },
>> +	{},
>> +};
>> +MODULE_DEVICE_TABLE(of, jz4780_bch_dt_match);
>> +
>> +static struct platform_driver jz4780_bch_driver = {
>> +	.probe		= jz4780_bch_probe,
> 
> Why no remove?

Is it needed? Everything should be cleaned up due to the use of devm functions.


>> +static int jz4780_nand_init_chips(struct jz4780_nand *nand, struct device *dev)
>> +{
>> +	struct jz4780_nand_chip *chip;
>> +	const __be32 *prop;
>> +	u64 addr, size;
>> +	int i = 0;
>> +
>> +	/*
>> +	 * Iterate over each bank assigned to this device and request resources.
>> +	 * The bank numbers may not be consecutive, but nand_scan_ident()
>> +	 * expects chip numbers to be, so fill out a consecutive array of chips
>> +	 * which map chip number to actual bank number.
>> +	 */
>> +	while ((prop = of_get_address(dev->of_node, i, &size, NULL))) {
>> +		chip = &nand->chips[i];
>> +		chip->bank = of_read_number(prop, 1);
>> +
>> +		jz4780_nemc_set_type(nand->dev, chip->bank,
>> +				     JZ4780_NEMC_BANK_NAND);
>> +
>> +		addr = of_translate_address(dev->of_node, prop);
> 
> Are you sure you must translate the address yourself?
> Isn't this handled by the OF magic behing the ranges property
> in the NEMC DT node?

I think the reasoning behind doing this was because I already have to get the address property here in order to get the bank number out of it.

You're right though that I can just do "platform_get_resource(pdev, i)" and avoid doing the translation again, so I have changed it to do that.

I've fixed the rest of your comments as well.

Thanks,
Alex
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Re: [PATCH v4 3/3] mtd: nand: jz4780: driver for NAND devices on JZ4780 SoCs

Contents

#1219864 — Re: [PATCH v4 3/3] mtd: nand: jz4780: driver for NAND devices on JZ4780 SoCs

#1220259