Date:	Mon, 4 Jan 2016 10:24:15 +0000
From:	Harvey Hunt <harvey.hunt@...tec.com>
To:	Boris Brezillon <boris.brezillon@...e-electrons.com>
CC:	<linux-mtd@...ts.infradead.org>, <computersforpeace@...il.com>,
	<alex@...x-smith.me.uk>, Alex Smith <alex.smith@...tec.com>,
	"Zubair Lutfullah Kakakhel" <Zubair.Kakakhel@...tec.com>,
	David Woodhouse <dwmw2@...radead.org>,
	<linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v10 2/3] mtd: nand: jz4780: driver for NAND devices on
 JZ4780 SoCs

Hi Boris,

Happy New Year.

Thanks for the comments - I'll send out a new patchset today.

On 28/12/15 08:25, Boris Brezillon wrote:
> Hi Harvey,
>
> I found a few remaining issues. Once fixed you can add my
>
> Reviewed-by: Boris Brezillon <boris.brezillon@...e-electrons.com>
>
> On Thu, 24 Dec 2015 12:20:14 +0000
> Harvey Hunt <harvey.hunt@...tec.com> wrote:
>
>> From: Alex Smith <alex.smith@...tec.com>
>>
>> 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.
>>
>> Signed-off-by: Alex Smith <alex.smith@...tec.com>
>> Cc: Zubair Lutfullah Kakakhel <Zubair.Kakakhel@...tec.com>
>> Cc: David Woodhouse <dwmw2@...radead.org>
>> Cc: Brian Norris <computersforpeace@...il.com>
>> Cc: linux-mtd@...ts.infradead.org
>> Cc: linux-kernel@...r.kernel.org
>> Signed-off-by: Harvey Hunt <harvey.hunt@...tec.com>
>> ---
>> v9 -> v10:
>>   - Replace uint{8,32}_t with u{8,32}.
>>   - Only set IO_ADDR_{R,W} during chip init.
>>   - Check that ECC layout fits into OOB area.
>>   - Rebase onto l2-mtd/master and use its new functions.
>>   - Remove mtd field from jz4780_nand_chip.
>>   - Tidied up jz4780_nand_cmd_ctrl.
>>   - Corrected ECC mode print statement.
>>   - Refactor BCH code.
>>   - Implement of_jz4780_bch_get.
>>   - Update Authorship.
>>   - Use a mutex to protect accesses to BCH controller.
>>   - Update code documentation.
>>   - Checkpatch cleanup.
>>
>> v8 -> v9:
>>   - No change.
>>
>> v7 -> v8:
>>   - Rebase to 4.4-rc3.
>>   - Add _US suffixes to time constants.
>>   - Add locking to BCH hardware accesses.
>>   - Don't print ECC info if ECC is not being used.
>>   - Default to No ECC.
>>   - Let the NAND core handle ECC layout in certain cases.
>>   - Use the gpio_desc consumer interface.
>>   - Removed gpio active low flags.
>>   - Check for the BCH controller before initialising a chip.
>>   - Add a jz4780_nand_controller struct.
>>   - Initialise chips by iterating over DT child nodes.
>>
>> v6 -> v7:
>>   - Add nand-ecc-mode to DT bindings.
>>   - Add nand-on-flash-bbt to DT bindings.
>>
>> v5 -> v6:
>>   - No change.
>>
>> v4 -> v5:
>>   - Rename ingenic,bch-device to ingenic,bch-controller to fit with
>>     existing convention.
>>
>> v3 -> v4:
>>   - No change
>>
>> v2 -> v3:
>>   - Rebase to 4.0-rc6
>>   - Changed ingenic,ecc-size to common nand-ecc-step-size
>>   - Changed ingenic,ecc-strength to common nand-ecc-strength
>>   - Changed ingenic,busy-gpio to common rb-gpios
>>   - Changed ingenic,wp-gpio to common wp-gpios
>>
>> v1 -> v2:
>>   - Rebase to 4.0-rc3
>>
>>   drivers/mtd/nand/Kconfig       |   7 +
>>   drivers/mtd/nand/Makefile      |   1 +
>>   drivers/mtd/nand/jz4780_bch.c  | 381 +++++++++++++++++++++++++++++++++++++
>>   drivers/mtd/nand/jz4780_bch.h  |  44 +++++
>>   drivers/mtd/nand/jz4780_nand.c | 416 +++++++++++++++++++++++++++++++++++++++++
>>   5 files changed, 849 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 2896640..b742adc 100644
>> --- a/drivers/mtd/nand/Kconfig
>> +++ b/drivers/mtd/nand/Kconfig
>> @@ -519,6 +519,13 @@ 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 2c7f014..9e36233 100644
>> --- a/drivers/mtd/nand/Makefile
>> +++ b/drivers/mtd/nand/Makefile
>> @@ -49,6 +49,7 @@ obj-$(CONFIG_MTD_NAND_MPC5121_NFC)	+= mpc5121_nfc.o
>>   obj-$(CONFIG_MTD_NAND_VF610_NFC)	+= vf610_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 0000000..22d3729
>> --- /dev/null
>> +++ b/drivers/mtd/nand/jz4780_bch.c
>> @@ -0,0 +1,381 @@
>> +/*
>> + * JZ4780 BCH controller
>> + *
>> + * Copyright (c) 2015 Imagination Technologies
>> + * Author: Alex Smith <alex.smith@...tec.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/bitops.h>
>> +#include <linux/clk.h>
>> +#include <linux/delay.h>
>> +#include <linux/init.h>
>> +#include <linux/iopoll.h>
>> +#include <linux/module.h>
>> +#include <linux/mutex.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. */
>> +#define BCH_TIMEOUT_US			100000
>> +
>> +struct jz4780_bch {
>> +	struct device *dev;
>> +	void __iomem *base;
>> +	struct clk *clk;
>> +	struct mutex lock;
>> +};
>> +
>> +static void jz4780_bch_init(struct jz4780_bch *bch,
>> +			    struct jz4780_bch_params *params, bool encode)
>> +{
>> +	u32 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);
>
> Not sure what BCH_BHCR_BCHE means, but if BCHE stands for "BCH Enable",
> do you really have to keep this bit set when disabling the engine?

The JZ4780 has the BHCR (BCH  Control Register) as well as the BHCCR 
(BCH Control Clear Register) and BHCSR (BCH Control Set Register). 
Setting the bit BCH_BHCR_BCHE in BHCCR clears the corresponding bit in 
BHCR, which disables the BCH controller.

>
>> +}
>> +
>
> [...]
>
>> +
>> +/**
>> + * jz4780_bch_calculate() - calculate ECC for a data buffer
>> + * @bch: 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 jz4780_bch *bch, struct jz4780_bch_params *params,
>> +			 const u8 *buf, u8 *ecc_code)
>> +{
>> +	int ret = 0;
>> +
>> +	mutex_lock(&bch->lock);
>> +	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(bch->dev, "timed out while calculating ECC\n");
>> +		ret = -ETIMEDOUT;
>> +	}
>> +
>> +	mutex_unlock(&bch->lock);
>> +	jz4780_bch_disable(bch);
>
> Is there a good reason to put jz4780_bch_disable() out of the protected
> section?

No good reason, I've fixed it.

>
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL(jz4780_bch_calculate);
>> +
>> +/**
>> + * jz4780_bch_correct() - detect and correct bit errors
>> + * @bch: 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 jz4780_bch *bch, struct jz4780_bch_params *params,
>> +		       u8 *buf, u8 *ecc_code)
>> +{
>> +	u32 reg, mask, index;
>> +	int i, ret, count;
>> +
>> +	mutex_lock(&bch->lock);
>> +
>> +	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(bch->dev, "timed out while correcting data\n");
>> +		ret = -1;
>> +		goto out;
>> +	}
>> +
>> +	if (reg & BCH_BHINT_UNCOR) {
>> +		dev_warn(bch->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:
>> +	mutex_unlock(&bch->lock);
>> +	jz4780_bch_disable(bch);
>
> Ditto.

As above.

>
>> +	return ret;
>> +}
>> +EXPORT_SYMBOL(jz4780_bch_correct);
>> +
>> +/**
>> + * jz4780_bch_get() - get the BCH controller device
>> + * @np: BCH device tree node.
>> + *
>> + * 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: a pointer to jz4780_bch, errors are encoded into the pointer.
>> + * PTR_ERR(-EPROBE_DEFER) if the device hasn't been initialised yet.
>> + */
>> +struct jz4780_bch *jz4780_bch_get(struct device_node *np)
>> +{
>> +	struct platform_device *pdev;
>> +	struct jz4780_bch *bch;
>> +
>> +	pdev = of_find_device_by_node(np);
>> +	if (!pdev || !platform_get_drvdata(pdev))
>> +		return ERR_PTR(-EPROBE_DEFER);
>> +
>> +	get_device(&pdev->dev);
>> +
>> +	bch = platform_get_drvdata(pdev);
>> +	clk_prepare_enable(bch->clk);
>> +
>> +	bch->dev = &pdev->dev;
>> +	return bch;
>> +}
>> +EXPORT_SYMBOL(jz4780_bch_get);
>
> You can keep this function private until someone really needs it (IOW,
> remove the EXPORT_SYMBOL line, the prototype definition in your header
> and add a static qualifier).

Done.

>
> [...]
>
>> diff --git a/drivers/mtd/nand/jz4780_bch.h b/drivers/mtd/nand/jz4780_bch.h
>> new file mode 100644
>> index 0000000..6e9581f
>> --- /dev/null
>> +++ b/drivers/mtd/nand/jz4780_bch.h
>> @@ -0,0 +1,44 @@
>> +/*
>> + * JZ4780 BCH controller
>> + *
>> + * Copyright (c) 2015 Imagination Technologies
>> + * Author: Alex Smith <alex.smith@...tec.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;
>> +
>> +/**
>> + * 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 jz4780_bch *bch,
>> +				struct jz4780_bch_params *params,
>> +				const u8 *buf, u8 *ecc_code);
>> +extern int jz4780_bch_correct(struct jz4780_bch *bch,
>> +			      struct jz4780_bch_params *params, u8 *buf,
>> +			      u8 *ecc_code);
>> +
>> +extern struct jz4780_bch *jz4780_bch_get(struct device_node *np);
>
> As said above, you should drop this definition.
>
>> +extern void jz4780_bch_release(struct jz4780_bch *bch);
>> +extern struct jz4780_bch *of_jz4780_bch_get(struct device_node *np);
>
> I'm nitpicking, but 'extern' is not needed for function prototype
> definitions.

I've made both of these changes.

>
>> +
>> +#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 0000000..3708d50
>> --- /dev/null
>> +++ b/drivers/mtd/nand/jz4780_nand.c
>> @@ -0,0 +1,416 @@
>> +/*
>> + * JZ4780 NAND driver
>> + *
>> + * Copyright (c) 2015 Imagination Technologies
>> + * Author: Alex Smith <alex.smith@...tec.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/list.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/of_address.h>
>> +#include <linux/gpio/consumer.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 DRV_NAME	"jz4780-nand"
>> +
>> +#define OFFSET_DATA	0x00000000
>> +#define OFFSET_CMD	0x00400000
>> +#define OFFSET_ADDR	0x00800000
>> +
>> +/* Command delay when there is no R/B pin. */
>> +#define RB_DELAY_US	100
>> +
>> +struct jz4780_nand_cs {
>> +	unsigned int bank;
>> +	void __iomem *base;
>> +};
>> +
>> +struct jz4780_nand_controller {
>> +	struct device *dev;
>> +	struct jz4780_bch *bch;
>> +	struct nand_hw_control controller;
>> +	unsigned int num_banks;
>> +	struct list_head chips;
>> +	int selected;
>> +	struct jz4780_nand_cs cs[];
>> +};
>> +
>> +struct jz4780_nand_chip {
>> +	struct nand_chip chip;
>> +	struct list_head chip_list;
>> +
>> +	struct nand_ecclayout ecclayout;
>> +
>> +	struct gpio_desc *busy_gpio;
>> +	struct gpio_desc *wp_gpio;
>> +	unsigned int reading: 1;
>> +};
>> +
>> +static inline struct jz4780_nand_chip *to_jz4780_nand_chip(struct mtd_info *mtd)
>> +{
>> +	return container_of(mtd_to_nand(mtd), struct jz4780_nand_chip, chip);
>> +}
>> +
>> +static inline struct jz4780_nand_controller *to_jz4780_nand_controller(struct nand_hw_control *ctrl)
>> +{
>> +	return container_of(ctrl, struct jz4780_nand_controller, controller);
>> +}
>> +
>> +static void jz4780_nand_select_chip(struct mtd_info *mtd, int chipnr)
>> +{
>> +	struct jz4780_nand_chip *nand = to_jz4780_nand_chip(mtd);
>> +	struct jz4780_nand_controller *nfc = to_jz4780_nand_controller(nand->chip.controller);
>> +	struct jz4780_nand_cs *cs;
>> +
>> +	if (chipnr == -1) {
>> +		/* Ensure the currently selected chip is deasserted. */
>> +		if (nfc->selected >= 0) {
>> +			cs = &nfc->cs[nfc->selected];
>> +			jz4780_nemc_assert(nfc->dev, cs->bank, false);
>> +		}
>> +	} else {
>> +		cs = &nfc->cs[chipnr];
>
> This else statement seems useless to me.

I've removed it.

>
>> +	}
>> +
>> +	nfc->selected = chipnr;
>> +}
>> +
>
> [...]
>
>> +
>> +static int jz4780_nand_init_ecc(struct jz4780_nand_chip *nand, struct device *dev)
>> +{
>> +	struct nand_chip *chip = &nand->chip;
>> +	struct mtd_info *mtd = nand_to_mtd(chip);
>> +	struct jz4780_nand_controller *nfc = to_jz4780_nand_controller(chip->controller);
>> +	struct nand_ecclayout *layout = &nand->ecclayout;
>> +	u32 start, i;
>> +
>> +	chip->ecc.bytes = fls((1 + 8) * chip->ecc.size)	*
>> +				(chip->ecc.strength / 8);
>> +
>> +	if (nfc->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 if (!nfc->bch && chip->ecc.mode == NAND_ECC_HW) {
>> +		dev_err(dev, "HW BCH selected, but BCH controller not found\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	if (chip->ecc.mode != NAND_ECC_NONE)
>> +		dev_info(dev, "using %s (strength %d, size %d, bytes %d)\n",
>> +			(nfc->bch) ? "hardware BCH" : "software hamming",
>
> As said in my previous review, '!= NAND_ECC_HW' does not necessarily
> imply '== NAND_ECC_SOFT' (i.e. hamming ECC), so I'd suggest printing
> something like "software ECC".

Done.

>
>> +			chip->ecc.strength, chip->ecc.size, chip->ecc.bytes);
>> +	else
>> +		dev_info(dev, "not using ECC\n");
>
> You should probably complain about the invalid NAND_ECC_HW_SYNDROME
> value and return -EINVAL in this case.
>
>> +
>> +	/* The NAND core will generate the ECC layout. */
>> +	if (chip->ecc.mode == NAND_ECC_SOFT || chip->ecc.mode == NAND_ECC_SOFT_BCH)
>> +		return 0;
>> +
>> +	/* Generate ECC layout. ECC codes are right aligned in the OOB area. */
>> +	layout->eccbytes = mtd->writesize / chip->ecc.size * chip->ecc.bytes;
>> +
>> +	if (layout->eccbytes > mtd->oobsize - 2) {
>> +		dev_err(dev,
>> +			"invalid ECC config: required %d ECC bytes, but only %d are available",
>> +			layout->eccbytes, mtd->oobsize - 2);
>> +		return -EINVAL;
>> +	}
>> +
>> +	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;
>> +	return 0;
>> +}
>> +
>> +static int jz4780_nand_init_chip(struct platform_device *pdev,
>> +				struct jz4780_nand_controller *nfc,
>> +				struct device_node *np,
>> +				unsigned int chipnr)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	struct jz4780_nand_chip *nand;
>> +	struct jz4780_nand_cs *cs;
>> +	struct resource *res;
>> +	struct nand_chip *chip;
>> +	struct mtd_info *mtd;
>> +	const __be32 *reg;
>> +	int ret = 0;
>> +
>> +	cs = &nfc->cs[chipnr];
>> +
>> +	reg = of_get_property(np, "reg", NULL);
>> +	if (!reg)
>> +		return -EINVAL;
>> +
>> +	cs->bank = be32_to_cpu(*reg);
>> +
>> +	jz4780_nemc_set_type(nfc->dev, cs->bank, JZ4780_NEMC_BANK_NAND);
>> +
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, chipnr);
>> +	cs->base = devm_ioremap_resource(dev, res);
>> +	if (IS_ERR(cs->base))
>> +		return PTR_ERR(cs->base);
>> +
>> +	nand = devm_kzalloc(dev, sizeof(*nand), GFP_KERNEL);
>> +	if (!nand)
>> +		return -ENOMEM;
>> +
>> +	nand->busy_gpio = devm_gpiod_get_optional(dev, "rb", GPIOD_IN);
>> +
>> +	if (IS_ERR(nand->busy_gpio)) {
>> +		ret = PTR_ERR(nand->busy_gpio);
>> +		dev_err(dev, "failed to request busy GPIO: %d\n", ret);
>> +		return ret;
>> +	} else if (nand->busy_gpio) {
>> +		nand->chip.dev_ready = jz4780_nand_dev_ready;
>> +	}
>> +
>> +	nand->wp_gpio = devm_gpiod_get_optional(dev, "wp", GPIOD_OUT_LOW);
>> +
>> +	if (IS_ERR(nand->wp_gpio)) {
>> +		ret = PTR_ERR(nand->wp_gpio);
>> +		dev_err(dev, "failed to request WP GPIO: %d\n", ret);
>> +		return ret;
>> +	}
>> +
>> +	chip = &nand->chip;
>> +	mtd = nand_to_mtd(chip);
>> +	mtd->priv = chip;
>> +	mtd->owner = THIS_MODULE;
>> +	mtd->name = DRV_NAME;
>> +	mtd->dev.parent = dev;
>> +
>> +	chip->IO_ADDR_R = cs->base + OFFSET_DATA;
>> +	chip->IO_ADDR_W = cs->base + OFFSET_DATA;
>> +	chip->chip_delay = RB_DELAY_US;
>> +	chip->options = NAND_NO_SUBPAGE_WRITE;
>> +	chip->select_chip = jz4780_nand_select_chip;
>> +	chip->cmd_ctrl = jz4780_nand_cmd_ctrl;
>> +	chip->ecc.mode = NAND_ECC_HW;
>> +	chip->controller = &nfc->controller;
>> +	nand_set_flash_node(chip, np);
>> +
>> +	ret = nand_scan_ident(mtd, 1, NULL);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = jz4780_nand_init_ecc(nand, dev);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = nand_scan_tail(mtd);
>> +	if (ret)
>> +		goto err_release_bch;
>> +
>> +	ret = mtd_device_register(mtd, NULL, 0);
>> +	if (ret)
>> +		goto err_release_nand;
>> +
>
> You probably miss a list_add_tail() call here (otherwise chips are
> registered but not unregistered when ->remove() is called):
>
> 	list_add_tail(&nand->chip_list, &nfc->chips);

Thanks for spotting this - I've fixed it now,

>
>> +	return 0;
>> +
>> +err_release_nand:
>> +	nand_release(mtd);
>> +
>> +err_release_bch:
>> +	if (nfc->bch)
>> +		jz4780_bch_release(nfc->bch);
>
> Why are you releasing the BCH engine here, isn't it the role of the
> NAND controller to do that? BTW, it's already done in
> jz4780_nand_remove().

I don't think jz4780_nand_remove() will get called if we fail to 
initialise the chips, so perhaps it would be better to move this into 
jz4780_nand_probe?

>
>> +
>> +	return ret;
>> +}
>> +
>> +static int jz4780_nand_init_chips(struct jz4780_nand_controller *nfc,
>> +				  struct platform_device *pdev)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	struct device_node *np;
>> +	int i = 0;
>> +	int ret;
>> +	int num_chips = of_get_child_count(dev->of_node);
>> +
>> +	if (num_chips > nfc->num_banks) {
>> +		dev_err(dev, "found %d chips but only %d banks\n", num_chips, nfc->num_banks);
>> +		return -EINVAL;
>> +	}
>> +
>> +	for_each_child_of_node(dev->of_node, np) {
>> +		ret = jz4780_nand_init_chip(pdev, nfc, np, i);
>> +		if (ret)
>> +			return ret;
>
> You should unregister all the chips already registered in case of
> failure. The same logic is already implemented in jz4780_nand_remove(),
> so I suggest implementing a jz4780_nand_cleanup_chips() function:
>
> static void jz4780_nand_cleanup_chips(struct jz4780_nand_controller
> *nfc)
> {
> 	struct jz4780_nand_chip *chip;
>
> 	while (!list_empty(&nfc->chips)) {
> 		chip = list_first_entry(&nfc->chips, struct
> 	jz4780_nand_chip, chip_list);
> 		nand_release(nand_to_mtd(&chip->chip));
> 		list_del(&chip->chip_list);
> 	}
> }

Done.

>
>> +
>> +		i++;
>> +	}
>> +
>> +	return 0;
>> +}
>> +
>> +static int jz4780_nand_probe(struct platform_device *pdev)
>> +{
>> +	struct device *dev = &pdev->dev;
>> +	unsigned int num_banks;
>> +	struct jz4780_nand_controller *nfc;
>> +	int ret;
>> +
>> +	num_banks = jz4780_nemc_num_banks(dev);
>> +	if (num_banks == 0) {
>> +		dev_err(dev, "no banks found\n");
>> +		return -ENODEV;
>> +	}
>> +
>> +	nfc = devm_kzalloc(dev, sizeof(*nfc) + (sizeof(nfc->cs[0]) * num_banks), GFP_KERNEL);
>> +	if (!nfc)
>> +		return -ENOMEM;
>> +
>> +	/*
>> +	 * Check for BCH HW before we call nand_scan_ident, to prevent us from
>> +	 * having to call it again if the BCH driver returns -EPROBE_DEFER.
>> +	 */
>> +	nfc->bch = of_jz4780_bch_get(dev->of_node);
>> +	if (IS_ERR(nfc->bch))
>> +		return PTR_ERR(nfc->bch);
>> +
>> +	nfc->dev = dev;
>> +	nfc->num_banks = num_banks;
>> +
>> +	spin_lock_init(&nfc->controller.lock);
>> +	INIT_LIST_HEAD(&nfc->chips);
>> +	init_waitqueue_head(&nfc->controller.wq);
>> +
>> +	ret = jz4780_nand_init_chips(nfc, pdev);
>> +	if (ret)
>> +		return ret;
>> +
>> +	platform_set_drvdata(pdev, nfc);
>> +	return 0;
>> +}
>> +
>> +static int jz4780_nand_remove(struct platform_device *pdev)
>> +{
>> +	struct jz4780_nand_chip *chip;
>> +	struct jz4780_nand_controller *nfc = platform_get_drvdata(pdev);
>> +
>> +	while (!list_empty(&nfc->chips)) {
>> +		chip = list_first_entry(&nfc->chips, struct jz4780_nand_chip, chip_list);
>> +		nand_release(nand_to_mtd(&chip->chip));
>> +		list_del(&chip->chip_list);
>> +	}
>
> Call jz4780_nand_cleanup_chips() here.

Done.

>
>> +
>> +	if (nfc->bch)
>> +		jz4780_bch_release(nfc->bch);
>> +
>> +	return 0;
>> +}
>> +
>
> Best Regards,
>
> Boris
>
>

Thanks,

Harvey
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