Date:   Sun, 6 Aug 2017 21:27:39 +0200
From:   Marek Vasut <marek.vasut@...il.com>
To:     matthew.gerlach@...ux.intel.com, vndao@...era.com,
        dwmw2@...radead.org, computersforpeace@...il.com,
        boris.brezillon@...e-electrons.com, richard@....at,
        cyrille.pitchen@...ev4u.fr, robh+dt@...nel.org,
        mark.rutland@....com, linux-mtd@...ts.infradead.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        gregkh@...uxfoundation.org, davem@...emloft.net,
        mchehab@...nel.org, linux-fpga@...r.kernel.org
Subject: Re: [PATCH 2/2] mtd: spi-nor: Altera ASMI Parallel II IP Core

On 08/06/2017 08:24 PM, matthew.gerlach@...ux.intel.com wrote:
> From: Matthew Gerlach <matthew.gerlach@...ux.intel.com>

Thanks for the descriptive commit message. Could you explain what this
patch is all about ?

> Signed-off-by: Matthew Gerlach <matthew.gerlach@...ux.intel.com>

[...]

> diff --git a/drivers/mtd/spi-nor/Makefile b/drivers/mtd/spi-nor/Makefile
> index c5f171d..1c79324 100644
> --- a/drivers/mtd/spi-nor/Makefile
> +++ b/drivers/mtd/spi-nor/Makefile
> @@ -1,4 +1,5 @@
>  obj-$(CONFIG_MTD_SPI_NOR)	+= spi-nor.o
> +obj-$(CONFIG_SPI_ALTERA_ASMIP2)	+= altera-asmip2.o
>  obj-$(CONFIG_SPI_ASPEED_SMC)	+= aspeed-smc.o
>  obj-$(CONFIG_SPI_ATMEL_QUADSPI)	+= atmel-quadspi.o
>  obj-$(CONFIG_SPI_CADENCE_QUADSPI)	+= cadence-quadspi.o
> @@ -9,4 +10,4 @@ obj-$(CONFIG_SPI_NXP_SPIFI)	+= nxp-spifi.o
>  obj-$(CONFIG_SPI_INTEL_SPI)	+= intel-spi.o
>  obj-$(CONFIG_SPI_INTEL_SPI_PCI)	+= intel-spi-pci.o
>  obj-$(CONFIG_SPI_INTEL_SPI_PLATFORM)	+= intel-spi-platform.o
> -obj-$(CONFIG_SPI_STM32_QUADSPI)	+= stm32-quadspi.o
> \ No newline at end of file
> +obj-$(CONFIG_SPI_STM32_QUADSPI)	+= stm32-quadspi.o

Drop this hunk

> diff --git a/drivers/mtd/spi-nor/altera-asmip2.c b/drivers/mtd/spi-nor/altera-asmip2.c
> new file mode 100644
> index 0000000..2095f2e
> --- /dev/null
> +++ b/drivers/mtd/spi-nor/altera-asmip2.c
> @@ -0,0 +1,474 @@
> +/*
> + * Copyright (C) 2017 Intel Corporation. All rights reserved.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along with
> + * this program.  If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/iopoll.h>
> +#include <linux/module.h>
> +#include <linux/mtd/altera-asmip2.h>
> +#include <linux/mtd/mtd.h>
> +#include <linux/mtd/spi-nor.h>
> +#include <linux/of_device.h>
> +
> +#define QSPI_ACTION_REG 0
> +#define QSPI_ACTION_RST BIT(0)
> +#define QSPI_ACTION_EN BIT(1)
> +#define QSPI_ACTION_SC BIT(2)
> +#define QSPI_ACTION_CHIP_SEL_SFT 4
> +#define QSPI_ACTION_DUMMY_SFT 8
> +#define QSPI_ACTION_READ_BACK_SFT 16
> +
> +#define QSPI_FIFO_CNT_REG 4
> +#define QSPI_FIFO_DEPTH 0x200
> +#define QSPI_FIFO_CNT_MSK 0x3ff
> +#define QSPI_FIFO_CNT_RX_SFT 0
> +#define QSPI_FIFO_CNT_TX_SFT 12

Indent the value with a tab at least ...

> +#define QSPI_DATA_REG 0x8
> +
> +#define QSPI_POLL_TIMEOUT 10000000

In what units is this ?

> +#define QSPI_POLL_INTERVAL 5
> +
> +struct altera_asmip2 {
> +	void __iomem *csr_base;
> +	u32 num_flashes;
> +	struct device *dev;
> +	struct altera_asmip2_flash *flash[ALTERA_ASMIP2_MAX_NUM_FLASH_CHIP];
> +	struct mutex bus_mutex;
> +};
> +
> +struct altera_asmip2_flash {
> +	struct spi_nor nor;
> +	struct altera_asmip2 *q;
> +	u32 bank;
> +};
> +
> +static int altera_asmip2_write_reg(struct spi_nor *nor, u8 opcode, u8 *val,
> +				    int len)
> +{
> +	struct altera_asmip2_flash *flash = nor->priv;
> +	struct altera_asmip2 *q = flash->q;
> +	u32 reg;
> +	int ret;
> +	int i;
> +
> +	if ((len + 1) > QSPI_FIFO_DEPTH) {
> +		dev_err(q->dev, "%s bad len %d > %d\n",
> +			__func__, len + 1, QSPI_FIFO_DEPTH);
> +		return -EINVAL;
> +	}
> +
> +	writel(opcode, q->csr_base + QSPI_DATA_REG);
> +
> +	for (i = 0; i < len; i++) {
> +		writel((u32)val[i], q->csr_base + QSPI_DATA_REG);

iowrite32_rep() ?

> +	}
> +
> +	reg = QSPI_ACTION_EN | QSPI_ACTION_SC;
> +
> +	writel(reg, q->csr_base + QSPI_ACTION_REG);
> +
> +	ret = readl_poll_timeout(q->csr_base + QSPI_FIFO_CNT_REG, reg,
> +				 (((reg >> QSPI_FIFO_CNT_TX_SFT) &
> +				 QSPI_FIFO_CNT_MSK) == 0), QSPI_POLL_INTERVAL,
> +				 QSPI_POLL_TIMEOUT);
> +	if (ret)
> +		dev_err(q->dev, "%s timed out\n", __func__);

So if the poll fails , you ignore the failure and continue enabling
whatever action you enable here ?

> +	reg = QSPI_ACTION_EN;
> +
> +	writel(reg, q->csr_base + QSPI_ACTION_REG);
> +
> +	return ret;
> +}
> +
> +static int altera_asmip2_read_reg(struct spi_nor *nor, u8 opcode, u8 *val,
> +				   int len)
> +{
> +	struct altera_asmip2_flash *flash = nor->priv;
> +	struct altera_asmip2 *q = flash->q;
> +	u32 reg;
> +	int ret;
> +	int i;
> +
> +	if (len > QSPI_FIFO_DEPTH) {
> +		dev_err(q->dev, "%s bad len %d > %d\n",
> +			__func__, len, QSPI_FIFO_DEPTH);
> +		return -EINVAL;
> +	}
> +
> +	writel(opcode, q->csr_base + QSPI_DATA_REG);
> +
> +	reg = QSPI_ACTION_EN | QSPI_ACTION_SC |
> +		(len << QSPI_ACTION_READ_BACK_SFT);
> +
> +	writel(reg, q->csr_base + QSPI_ACTION_REG);
> +
> +	ret = readl_poll_timeout(q->csr_base + QSPI_FIFO_CNT_REG, reg,
> +				 ((reg & QSPI_FIFO_CNT_MSK) == len),
> +				 QSPI_POLL_INTERVAL, QSPI_POLL_TIMEOUT);
> +
> +	if (!ret)
> +		for (i = 0; i < len; i++) {
> +			reg = readl(q->csr_base + QSPI_DATA_REG);
> +			val[i] = (u8)(reg & 0xff);

ioread32_rep , plus same comments as for the write function

> +		}
> +	else
> +		dev_err(q->dev, "%s timeout\n", __func__);
> +
> +	writel(QSPI_ACTION_EN, q->csr_base + QSPI_ACTION_REG);
> +
> +	return ret;
> +}
> +
> +static ssize_t altera_asmip2_read(struct spi_nor *nor, loff_t from, size_t len,
> +				   u_char *buf)
> +{
> +	struct altera_asmip2_flash *flash = nor->priv;
> +	struct altera_asmip2 *q = flash->q;
> +	size_t bytes_to_read, i;
> +	u32 reg;
> +	int ret;
> +
> +	bytes_to_read = min_t(size_t, len, QSPI_FIFO_DEPTH);
> +
> +	writel(nor->read_opcode, q->csr_base + QSPI_DATA_REG);
> +
> +	writel((from & 0xff000000) >> 24, q->csr_base + QSPI_DATA_REG);
> +	writel((from & 0x00ff0000) >> 16, q->csr_base + QSPI_DATA_REG);
> +	writel((from & 0x0000ff00) >> 8, q->csr_base + QSPI_DATA_REG);
> +	writel((from & 0x000000ff), q->csr_base + QSPI_DATA_REG);

Use a for() loop ?

> +	reg = QSPI_ACTION_EN | QSPI_ACTION_SC |
> +		(10 << QSPI_ACTION_DUMMY_SFT) |
> +		(bytes_to_read << QSPI_ACTION_READ_BACK_SFT);
> +
> +	writel(reg, q->csr_base + QSPI_ACTION_REG);
> +
> +	ret = readl_poll_timeout(q->csr_base + QSPI_FIFO_CNT_REG, reg,
> +				 ((reg & QSPI_FIFO_CNT_MSK) ==
> +				 bytes_to_read), QSPI_POLL_INTERVAL,
> +				 QSPI_POLL_TIMEOUT);
> +	if (ret) {
> +		dev_err(q->dev, "%s timed out\n", __func__);
> +		bytes_to_read = 0;
> +	} else
> +		for (i = 0; i < bytes_to_read; i++) {
> +			reg = readl(q->csr_base + QSPI_DATA_REG);
> +			*buf++ = (u8)(reg & 0xff);

ioread8_rep or something ?

> +		}
> +
> +	writel(QSPI_ACTION_EN, q->csr_base + QSPI_ACTION_REG);
> +
> +	return bytes_to_read;
> +}
> +
> +static ssize_t altera_asmip2_write(struct spi_nor *nor, loff_t to,
> +				    size_t len, const u_char *buf)
> +{
> +	struct altera_asmip2_flash *flash = nor->priv;
> +	struct altera_asmip2 *q = flash->q;
> +	size_t bytes_to_write, i;
> +	u32 reg;
> +	int ret;
> +
> +	bytes_to_write = min_t(size_t, len, (QSPI_FIFO_DEPTH - 5));
> +
> +	writel(nor->program_opcode, q->csr_base + QSPI_DATA_REG);
> +
> +	writel((to & 0xff000000) >> 24, q->csr_base + QSPI_DATA_REG);
> +	writel((to & 0x00ff0000) >> 16, q->csr_base + QSPI_DATA_REG);
> +	writel((to & 0x0000ff00) >> 8, q->csr_base + QSPI_DATA_REG);
> +	writel((to & 0x000000ff), q->csr_base + QSPI_DATA_REG);
> +
> +	for (i = 0; i < bytes_to_write; i++) {
> +		reg = (u32)*buf++;
> +		writel(reg, q->csr_base + QSPI_DATA_REG);
> +	}
> +
> +	reg = QSPI_ACTION_EN | QSPI_ACTION_SC;
> +
> +	writel(reg, q->csr_base + QSPI_ACTION_REG);
> +
> +	ret = readl_poll_timeout(q->csr_base + QSPI_FIFO_CNT_REG, reg,
> +				 (((reg >> QSPI_FIFO_CNT_TX_SFT) &
> +				 QSPI_FIFO_CNT_MSK) == 0), QSPI_POLL_INTERVAL,
> +				 QSPI_POLL_TIMEOUT);
> +
> +	if (ret) {
> +		dev_err(q->dev,
> +			"%s timed out waiting for fifo to clear\n",
> +			__func__);
> +		bytes_to_write = 0;
> +	}
> +
> +	writel(QSPI_ACTION_EN, q->csr_base + QSPI_ACTION_REG);
> +
> +	return bytes_to_write;
> +
> +}
> +
> +static int altera_asmip2_prep(struct spi_nor *nor, enum spi_nor_ops ops)
> +{
> +	struct altera_asmip2_flash *flash = nor->priv;
> +	struct altera_asmip2 *q = flash->q;
> +
> +	mutex_lock(&q->bus_mutex);

We should factor this mutex stuff into the SPI NOR framework, this
pattern is repeating itself way too often.

> +	return 0;
> +}
> +
> +static void altera_asmip2_unprep(struct spi_nor *nor, enum spi_nor_ops ops)
> +{
> +	struct altera_asmip2_flash *flash = nor->priv;
> +	struct altera_asmip2 *q = flash->q;
> +
> +	mutex_unlock(&q->bus_mutex);
> +}
> +
> +static int altera_asmip2_setup_banks(struct device *dev,
> +				      u32 bank, struct device_node *np)
> +{
> +	const struct spi_nor_hwcaps hwcaps = {
> +		.mask = SNOR_HWCAPS_READ |
> +			SNOR_HWCAPS_READ_FAST |
> +			SNOR_HWCAPS_PP,
> +	};
> +	struct altera_asmip2 *q = dev_get_drvdata(dev);
> +	struct altera_asmip2_flash *flash;
> +	struct spi_nor *nor;
> +	int ret = 0;
> +	char modalias[40] = {0};
> +
> +	if (bank > q->num_flashes - 1)
> +		return -EINVAL;
> +
> +	flash = devm_kzalloc(q->dev, sizeof(*flash), GFP_KERNEL);
> +	if (!flash)
> +		return -ENOMEM;
> +
> +	q->flash[bank] = flash;
> +	flash->q = q;
> +	flash->bank = bank;
> +
> +	nor = &flash->nor;
> +	nor->dev = dev;
> +	nor->priv = flash;
> +	nor->mtd.priv = nor;
> +	spi_nor_set_flash_node(nor, np);
> +
> +	/* spi nor framework*/
> +	nor->read_reg = altera_asmip2_read_reg;
> +	nor->write_reg = altera_asmip2_write_reg;
> +	nor->read = altera_asmip2_read;
> +	nor->write = altera_asmip2_write;
> +	nor->prepare = altera_asmip2_prep;
> +	nor->unprepare = altera_asmip2_unprep;
> +
> +	/* scanning flash and checking dev id */
> +#ifdef CONFIG_OF

Why is this here ?

> +	if (np && (of_modalias_node(np, modalias, sizeof(modalias)) < 0))
> +		return -EINVAL;
> +#endif
> +
> +	ret = spi_nor_scan(nor, modalias, &hwcaps);
> +	if (ret) {
> +		dev_err(nor->dev, "flash not found\n");
> +		return ret;
> +	}
> +
> +	ret =  mtd_device_register(&nor->mtd, NULL, 0);
> +
> +	return ret;
> +}
> +
> +static int altera_asmip2_create(struct device *dev, void __iomem *csr_base)
> +{
> +	struct altera_asmip2 *q;
> +	u32 reg;
> +
> +	q = devm_kzalloc(dev, sizeof(*q), GFP_KERNEL);
> +	if (!q)
> +		return -ENOMEM;
> +
> +	q->dev = dev;
> +	q->csr_base = csr_base;
> +
> +	mutex_init(&q->bus_mutex);
> +
> +	dev_set_drvdata(dev, q);
> +
> +	reg = readl(q->csr_base + QSPI_ACTION_REG);
> +	if (!(reg & QSPI_ACTION_RST)) {
> +		writel((reg | QSPI_ACTION_RST), q->csr_base + QSPI_ACTION_REG);
> +		dev_info(dev, "%s asserting reset\n", __func__);
> +		udelay(10);
> +	}
> +
> +	writel((reg & ~QSPI_ACTION_RST), q->csr_base + QSPI_ACTION_REG);
> +	udelay(10);
> +
> +	return 0;
> +}
> +
> +static int altera_qspi_add_bank(struct device *dev,
> +			 u32 bank, struct device_node *np)
> +{
> +	struct altera_asmip2 *q = dev_get_drvdata(dev);
> +
> +	if (q->num_flashes >= ALTERA_ASMIP2_MAX_NUM_FLASH_CHIP)
> +		return -ENOMEM;
> +
> +	q->num_flashes++;
> +
> +	return altera_asmip2_setup_banks(dev, bank, np);
> +}
> +
> +static int altera_asmip2_remove_banks(struct device *dev)
> +{
> +	struct altera_asmip2 *q = dev_get_drvdata(dev);
> +	struct altera_asmip2_flash *flash;
> +	int i;
> +	int ret = 0;
> +
> +	if (!q)
> +		return -EINVAL;
> +
> +	/* clean up for all nor flash */
> +	for (i = 0; i < q->num_flashes; i++) {
> +		flash = q->flash[i];
> +		if (!flash)
> +			continue;
> +
> +		/* clean up mtd stuff */
> +		ret = mtd_device_unregister(&flash->nor.mtd);
> +		if (ret) {
> +			dev_err(dev, "error removing mtd\n");
> +			return ret;
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static int __probe_with_data(struct platform_device *pdev,
> +			     struct altera_asmip2_plat_data *qdata)
> +{
> +	struct device *dev = &pdev->dev;
> +	int ret, i;
> +
> +	ret = altera_asmip2_create(dev, qdata->csr_base);
> +
> +	if (ret) {
> +		dev_err(dev, "failed to create qspi device %d\n", ret);
> +		return ret;
> +	}
> +
> +	for (i = 0; i < qdata->num_chip_sel; i++) {
> +		ret = altera_qspi_add_bank(dev, i, NULL);
> +		if (ret) {
> +			dev_err(dev, "failed to add qspi bank %d\n", ret);
> +			break;
> +		}
> +	}
> +
> +	return ret;
> +}
> +
> +static int altera_asmip2_probe(struct platform_device *pdev)
> +{
> +	struct device_node *np = pdev->dev.of_node;
> +	struct device *dev = &pdev->dev;
> +	struct altera_asmip2_plat_data *qdata;
> +	struct resource *res;
> +	void __iomem *csr_base;
> +	u32 bank;
> +	int ret;
> +	struct device_node *pp;
> +
> +	qdata = dev_get_platdata(dev);
> +
> +	if (qdata)
> +		return __probe_with_data(pdev, qdata);

Avoid function names with __ prefix.

> +	if (!np) {
> +		dev_err(dev, "no device tree found %p\n", pdev);
> +		return -ENODEV;
> +	}

You might as well introduce a function to probe with of to be consistent
... or convert between pdata and ofdata and have one function for both.

> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	csr_base = devm_ioremap_resource(dev, res);
> +	if (IS_ERR(csr_base)) {
> +		dev_err(dev, "%s: ERROR: failed to map csr base\n", __func__);
> +		return PTR_ERR(csr_base);
> +	}
> +
> +	ret = altera_asmip2_create(dev, csr_base);
> +
> +	if (ret) {
> +		dev_err(dev, "failed to create qspi device\n");
> +		return ret;
> +	}
> +
> +	for_each_available_child_of_node(np, pp) {
> +		of_property_read_u32(pp, "reg", &bank);
> +		if (bank >= ALTERA_ASMIP2_MAX_NUM_FLASH_CHIP) {
> +			dev_err(dev, "bad reg value %u >= %u\n", bank,
> +				ALTERA_ASMIP2_MAX_NUM_FLASH_CHIP);
> +			goto error;
> +		}
> +
> +		if (altera_qspi_add_bank(dev, bank, pp)) {
> +			dev_err(dev, "failed to add bank %u\n", bank);
> +			goto error;
> +		}
> +	}
> +
> +	return 0;
> +error:
> +	altera_asmip2_remove_banks(dev);
> +	return -EIO;
> +}
> +
> +static int altera_asmip2_remove(struct platform_device *pdev)
> +{
> +	if (!pdev) {
> +		dev_err(&pdev->dev, "%s NULL\n", __func__);
> +		return -EINVAL;

Can this really happen ?

> +	} else {
> +		return altera_asmip2_remove_banks(&pdev->dev);
> +	}
> +}
> +
> +static const struct of_device_id altera_asmip2_id_table[] = {
> +
> +	{ .compatible = "altr,asmi_parallel2",},
> +	{}
> +};
> +MODULE_DEVICE_TABLE(of, altera_asmip2_id_table);
> +
> +static struct platform_driver altera_asmip2_driver = {
> +	.driver = {
> +		.name = ALTERA_ASMIP2_DRV_NAME,
> +		.of_match_table = altera_asmip2_id_table,
> +	},
> +	.probe = altera_asmip2_probe,
> +	.remove = altera_asmip2_remove,
> +};
> +module_platform_driver(altera_asmip2_driver);
> +
> +MODULE_AUTHOR("Matthew Gerlach <matthew.gerlach@...ux.intel.com>");
> +MODULE_DESCRIPTION("Altera ASMI Parallel II");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("platform:" ALTERA_ASMIP2_DRV_NAME);
> diff --git a/include/linux/mtd/altera-asmip2.h b/include/linux/mtd/altera-asmip2.h
> new file mode 100644
> index 0000000..580c43c
> --- /dev/null
> +++ b/include/linux/mtd/altera-asmip2.h
> @@ -0,0 +1,24 @@
> +/*
> + *
> + * Copyright 2017 Intel Corporation, Inc.
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + */
> +#ifndef __ALTERA_QUADSPI_H
> +#define __ALTERA_QUADSPI_H
> +
> +#include <linux/device.h>
> +
> +#define ALTERA_ASMIP2_DRV_NAME "altr-asmip2"
> +#define ALTERA_ASMIP2_MAX_NUM_FLASH_CHIP 3
> +#define ALTERA_ASMIP2_RESOURCE_SIZE 0x10
> +
> +struct altera_asmip2_plat_data {
> +	void __iomem *csr_base;
> +	u32 num_chip_sel;
> +};
> +
> +#endif
> 


-- 
Best regards,
Marek Vasut

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