Message-ID: <5666FF6B.5090309@imgtec.com>
Date:	Tue, 8 Dec 2015 16:03:55 +0000
From:	Harvey Hunt <harvey.hunt@...tec.com>
To:	Boris Brezillon <boris.brezillon@...e-electrons.com>
CC:	<linux-mtd@...ts.infradead.org>,
	Zubair Lutfullah Kakakhel <Zubair.Kakakhel@...tec.com>,
	<linux-kernel@...r.kernel.org>, Alex Smith <alex.smith@...tec.com>,
	Brian Norris <computersforpeace@...il.com>,
	"David Woodhouse" <dwmw2@...radead.org>
Subject: Re: [PATCH v9 2/3] mtd: nand: jz4780: driver for NAND devices on
 JZ4780 SoCs

Hi Boris,

Thanks for the review.

On 08/12/15 14:14, Boris Brezillon wrote:
> On Thu, 3 Dec 2015 12:02:21 +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>
>> ---
>> 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  | 361 +++++++++++++++++++++++++++++++++++
>>   drivers/mtd/nand/jz4780_bch.h  |  42 +++++
>>   drivers/mtd/nand/jz4780_nand.c | 420 +++++++++++++++++++++++++++++++++++++++++
>>   5 files changed, 831 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..0c472f4
>> --- /dev/null
>> +++ b/drivers/mtd/nand/jz4780_bch.c
>> @@ -0,0 +1,361 @@
>> +/*
>> + * 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/of.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/sched.h>
>> +#include <linux/slab.h>
>> +#include <linux/spinlock.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 {
>> +	void __iomem *base;
>> +	struct clk *clk;
>> +	spinlock_t lock;
>
> Do you really need to protect accesses to the ECC engine with a
> spinlock...
>
>> +};
>> +
>
> [...]
>
>> +
>> +/**
>> + * 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;
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&bch->lock, flags);
>
> ... and disable the interrupts while doing so? I mean, the MTD layer is
> not supposed to call ->read()/->write() methods in irq context, so
> using a mutex here should be perfectly fine (at least for the NAND
> usage).
>

You're right, I underestimated the amount of time the spinlock would be 
held for. I also didn't realise that ->read()/->write() weren't called 
in IRQ context - I'll replace the spinlock with a mutex.

>> +
>> +	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;
>> +	}
>> +
>> +	spin_unlock_irqrestore(&bch->lock, flags);
>> +	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;
>
> Prefer u32/u16/u8 to the standard uint32_t/uint16_t/uint8_t definitions
> when you are developing kernel code.
>

Ack.

>> +	int i, ret, count;
>> +	unsigned long flags;
>> +
>> +	spin_lock_irqsave(&bch->lock, flags);
>> +
>> +	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:
>> +	spin_unlock_irqrestore(&bch->lock, flags);
>> +	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)
>
> You can just return a struct device * value and use the ERR_PTR() macro
> to cast an error code to a pointer. The caller can then test for the
> error case by doing IS_ERR(ret), and extract the corresponding error
> using PTR_ERR().

Okay, will do.

> Also, I don't think you need to return a struct device pointer here. How
> about just returning a struct jz4780_bch pointer and defining an opaque
> type in jz4780_bch.h (a single 'struct jz4780_bch;' statement).
> This would ease public jz4780_bch_xx() functions implementation (no
> need to extract the jz4780_bch pointer from the device one) and hide the
> jz4780_bch internals (the user doesn't have to know that the jz4780_bch
> device is actually attached to a struct device).
>

I like the idea of using an opaque type, I'll do this.

>
>> +{
>> +	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))
>> +		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);
>> +
>> +	spin_lock_init(&bch->lock);
>> +
>> +	platform_set_drvdata(pdev, bch);
>> +	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,
>> +	.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@...tec.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 0000000..a5dfde5
>> --- /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@...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_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 0000000..b4d0acb
>> --- /dev/null
>> +++ b/drivers/mtd/nand/jz4780_nand.c
>> @@ -0,0 +1,420 @@
>> +/*
>> + * 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 device *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 mtd_info mtd;
>> +	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, struct jz4780_nand_chip, mtd);
>> +}
>> +
>> +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];
>> +		nand->chip.IO_ADDR_R = cs->base + OFFSET_DATA;
>> +		nand->chip.IO_ADDR_W = cs->base + OFFSET_DATA;
>
> IO_ADDR_R/IO_ADDR_W assignments should only be done once when
> instantiating/initializing the nand_chip device...

Ack.

>
>> +	}
>> +
>> +	nfc->selected = chipnr;
>> +}
>> +
>> +static void jz4780_nand_cmd_ctrl(struct mtd_info *mtd, int cmd,
>> +				 unsigned int ctrl)
>> +{
>> +	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 (WARN_ON(nfc->selected < 0))
>> +		return;
>> +
>> +	cs = &nfc->cs[nfc->selected];
>> +
>> +	if (ctrl & NAND_CTRL_CHANGE) {
>> +		if (ctrl & NAND_ALE)
>> +			nand->chip.IO_ADDR_W = cs->base + OFFSET_ADDR;
>> +		else if (ctrl & NAND_CLE)
>> +			nand->chip.IO_ADDR_W = cs->base + OFFSET_CMD;
>> +		else
>> +			nand->chip.IO_ADDR_W = cs->base + OFFSET_DATA;
>> +		jz4780_nemc_assert(nfc->dev, cs->bank, ctrl & NAND_NCE);
>> +	}
>> +
>> +	if (cmd != NAND_CMD_NONE)
>> +		writeb(cmd, nand->chip.IO_ADDR_W);
>> +}
>
> ... and, as I said in my previous review, I don't think this IO_ADDR_W
> pointer assignment dance is worth it. AFAICS, the only thing it is used
> for are the read/write_byte/buf/word default implementation.
>
> The following code does exactly the same, and is, IMHO, clearer than
> changing the IO_ADDR_W address depending on the operation.
>
> static void jz4780_nand_cmd_ctrl(struct mtd_info *mtd, int cmd,
> 				 unsigned int ctrl)
> {
> 	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 (WARN_ON(nfc->selected < 0))
> 		return;
>
> 	cs = &nfc->cs[nfc->selected];
>
> 	if (ctrl & NAND_CTRL_CHANGE) {
> 		if (cmd != NAND_CMD_NONE) {
> 			if (ctrl & NAND_ALE)
> 				writeb(cmd, cs->base + OFFSET_ADDR);
> 			else if (ctrl & NAND_CLE)
> 				writeb(cmd, cs->base + OFFSET_CMD);
> 		}
>
> 		jz4780_nemc_assert(nfc->dev, cs->bank, ctrl & NAND_NCE);
> 	}
> }
>

Okay, I understand your point now. I would also have to implement the 
read/write functions to replace the defaults, correct? If so, it feels 
strange to add functions to reimplement the default ones.

>> +
>> +static int jz4780_nand_dev_ready(struct mtd_info *mtd)
>> +{
>> +	struct jz4780_nand_chip *nand = to_jz4780_nand_chip(mtd);
>> +
>> +	return !gpiod_get_value_cansleep(nand->busy_gpio);
>> +}
>> +
>> +static void jz4780_nand_ecc_hwctl(struct mtd_info *mtd, int mode)
>> +{
>> +	struct jz4780_nand_chip *nand = to_jz4780_nand_chip(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_chip *nand = to_jz4780_nand_chip(mtd);
>> +	struct jz4780_nand_controller *nfc = to_jz4780_nand_controller(nand->chip.controller);
>> +	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(nfc->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_chip *nand = to_jz4780_nand_chip(mtd);
>> +	struct jz4780_nand_controller *nfc = to_jz4780_nand_controller(nand->chip.controller);
>> +	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(nfc->bch, &params, dat, read_ecc);
>> +}
>> +
>> +static int jz4780_nand_init_ecc(struct jz4780_nand_chip *nand, struct device *dev)
>> +{
>> +	struct mtd_info *mtd = &nand->mtd;
>> +	struct nand_chip *chip = &nand->chip;
>> +	struct jz4780_nand_controller *nfc = to_jz4780_nand_controller(nand->chip.controller);
>> +	struct nand_ecclayout *layout = &nand->ecclayout;
>> +	uint32_t 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 BCH (strength %d, size %d, bytes %d)\n",
>
> if mode == NAND_ECC_SOFT we're not using BCH but hamming. Maybe you
> don't have to be so specific. Just saying that you're using software
> or hardware ECC should be enough.

Okay, I'll fix that.

>
>> +			(nfc->bch) ? "hardware" : "software", chip->ecc.strength,
>> +			chip->ecc.size, chip->ecc.bytes);
>> +	else
>> +		dev_info(dev, "not using ECC\n");
>> +
>> +	/* 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;
>
> You don't seem to check if the number of eccbytes fit into the available
> oobsize.
>
> 	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;
> 	}

I'll add this check.

>
>> +	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;
>> +	struct mtd_part_parser_data ppdata;
>> +	int ret = 0;
>> +
>> +	cs = &nfc->cs[chipnr];
>> +
>> +	reg = of_get_property(np, "reg", NULL);
>> +	if (reg == NULL)
>> +		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;
>> +	}
>> +
>> +	mtd = &nand->mtd;
>> +	chip = &nand->chip;
>> +	mtd->priv = chip;
>> +	mtd->owner = THIS_MODULE;
>> +	mtd->name = DRV_NAME;
>> +	mtd->dev.parent = dev;
>> +
>> +	chip->flash_node = np;
>
> Use the recently introduced
> 	nand_set_flash_node(chip, np);

Okay, will do.

As mentioned on IRC, I'll rebase onto l2-mtd.

>
>> +	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;
>> +
>> +	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;
>> +
>> +	ppdata.of_node = np;
>> +	ret = mtd_device_parse_register(mtd, NULL, &ppdata, NULL, 0);
>
> This has recently changed: you don't have to pass the of_node through
> the pdata structure anymore, it is automatically extracted from the
> mtd device if you've used nand_set_flash_node().
>
> Replace this call by
>
> 	ret = mtd_device_register(mtd, NULL, 0);

That looks much neater, I'll switch to that for the next version.

>
>
>> +	if (ret)
>> +		goto err_release_nand;
>> +
>> +	return 0;
>> +
>> +err_release_nand:
>> +	nand_release(mtd);
>> +
>> +err_release_bch:
>> +	if (nfc->bch)
>> +		jz4780_bch_release(nfc->bch);
>> +
>> +	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;
>> +
>> +		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;
>> +	struct device_node *bch_np;
>> +	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.
>> +	 */
>> +	bch_np = of_parse_phandle(dev->of_node,
>> +				"ingenic,bch-controller", 0);
>> +	if (bch_np) {
>> +		ret = jz4780_bch_get(bch_np, &nfc->bch);
>> +		of_node_put(bch_np);
>> +		if (ret)
>> +			return ret;
>> +	}
>
> This should probably be part of the API exposed by the jz4780_bch driver.
> Something like:
>
> struct jz4780_bch *of_jz4780_bch_get(struct device_node *np)
> {
> 	...
> }
>
> You could even provide a devm_ variant to simplify the cleanup path...

I agree, it'll look nicer - I'll make that change also.

>
> That's all I got for now :-).
> BTW, thanks for reworking the driver to match the controller/chip
> model.
>

No problem. :-)

Thanks again,

Harvey

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