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Message-ID: <fc2900acfbcdeeef0a3a9c8339aedada@agner.ch>
Date: Mon, 28 May 2018 14:41:05 +0200
From: Stefan Agner <stefan@...er.ch>
To: Miquel Raynal <miquel.raynal@...tlin.com>
Cc: boris.brezillon@...tlin.com, dwmw2@...radead.org,
computersforpeace@...il.com, marek.vasut@...il.com,
robh+dt@...nel.org, mark.rutland@....com, thierry.reding@...il.com,
mturquette@...libre.com, sboyd@...nel.org, dev@...xeye.de,
richard@....at, marcel@...wiler.com, krzk@...nel.org,
digetx@...il.com, benjamin.lindqvist@...ian.se,
jonathanh@...dia.com, pdeschrijver@...dia.com, pgaikwad@...dia.com,
mirza.krak@...il.com, linux-mtd@...ts.infradead.org,
linux-tegra@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org
Subject: Re: [PATCH v2 3/6] mtd: rawnand: add NVIDIA Tegra NAND Flash
controller driver
On 28.05.2018 00:19, Miquel Raynal wrote:
> Hi Stefan,
>
> A few more comments here.
>
> On Sun, 27 May 2018 23:54:39 +0200, Stefan Agner <stefan@...er.ch>
> wrote:
>
>> Add support for the NAND flash controller found on NVIDIA
>> Tegra 2 SoCs. This implementation does not make use of the
>> command queue feature. Regular operations/data transfers are
>> done in PIO mode. Page read/writes with hardware ECC make
>> use of the DMA for data transfer.
>>
>> Signed-off-by: Lucas Stach <dev@...xeye.de>
>> Signed-off-by: Stefan Agner <stefan@...er.ch>
>> ---
>> MAINTAINERS | 7 +
>> drivers/mtd/nand/raw/Kconfig | 6 +
>> drivers/mtd/nand/raw/Makefile | 1 +
>> drivers/mtd/nand/raw/tegra_nand.c | 999 ++++++++++++++++++++++++++++++
>> 4 files changed, 1013 insertions(+)
>> create mode 100644 drivers/mtd/nand/raw/tegra_nand.c
>>
>> diff --git a/MAINTAINERS b/MAINTAINERS
>> index 58b9861ccf99..8cbbb7111742 100644
>> --- a/MAINTAINERS
>> +++ b/MAINTAINERS
>> @@ -13844,6 +13844,13 @@ M: Laxman Dewangan <ldewangan@...dia.com>
>> S: Supported
>> F: drivers/input/keyboard/tegra-kbc.c
>>
>> +TEGRA NAND DRIVER
>> +M: Stefan Agner <stefan@...er.ch>
>> +M: Lucas Stach <dev@...xeye.de>
>> +S: Maintained
>> +F: Documentation/devicetree/bindings/mtd/nvidia,tegra20-nand.txt
>
> I think most MTD bindings use '-' instead of ','. I don't have a
> preference, it's just for coherence.
>
Sure, will use a dash.
>> +F: drivers/mtd/nand/raw/tegra_nand.c
>> +
>> TEGRA PWM DRIVER
>> M: Thierry Reding <thierry.reding@...il.com>
>> S: Supported
>> diff --git a/drivers/mtd/nand/raw/Kconfig b/drivers/mtd/nand/raw/Kconfig
>> index 19a2b283fbbe..012c63c6ab47 100644
>> --- a/drivers/mtd/nand/raw/Kconfig
>> +++ b/drivers/mtd/nand/raw/Kconfig
>> @@ -534,4 +534,10 @@ config MTD_NAND_MTK
>> Enables support for NAND controller on MTK SoCs.
>> This controller is found on mt27xx, mt81xx, mt65xx SoCs.
>>
>> +config MTD_NAND_TEGRA
>> + tristate "Support for NAND on NVIDIA Tegra"
>> + depends on ARCH_TEGRA || COMPILE_TEST
>> + help
>> + Enables support for NAND flash on NVIDIA Tegra SoC based boards.
>
> Please make the term "controller" appear because it's mostly a
> controller driver that you're adding.
>
Ok.
>> +
>> endif # MTD_NAND
>> diff --git a/drivers/mtd/nand/raw/Makefile b/drivers/mtd/nand/raw/Makefile
>> index 165b7ef9e9a1..d5a5f9832b88 100644
>> --- a/drivers/mtd/nand/raw/Makefile
>> +++ b/drivers/mtd/nand/raw/Makefile
>> @@ -56,6 +56,7 @@ obj-$(CONFIG_MTD_NAND_HISI504) += hisi504_nand.o
>> obj-$(CONFIG_MTD_NAND_BRCMNAND) += brcmnand/
>> obj-$(CONFIG_MTD_NAND_QCOM) += qcom_nandc.o
>> obj-$(CONFIG_MTD_NAND_MTK) += mtk_ecc.o mtk_nand.o
>> +obj-$(CONFIG_MTD_NAND_TEGRA) += tegra_nand.o
>>
>> nand-objs := nand_base.o nand_bbt.o nand_timings.o nand_ids.o
>> nand-objs += nand_amd.o
>
> [...]
>
>> +static int tegra_nand_setup_data_interface(struct mtd_info *mtd, int csline,
>> + const struct nand_data_interface *conf)
>> +{
>> + struct nand_chip *chip = mtd_to_nand(mtd);
>> + struct tegra_nand_controller *ctrl = to_tegra_ctrl(chip->controller);
>> + const struct nand_sdr_timings *timings;
>> +
>> + timings = nand_get_sdr_timings(conf);
>> + if (IS_ERR(timings))
>> + return PTR_ERR(timings);
>> +
>> + if (csline == NAND_DATA_IFACE_CHECK_ONLY)
>> + return 0;
>> +
>> + tegra_nand_setup_timing(ctrl, timings);
>
> Is this indirection really needed?
>
This evolved due to historic reasons, will get rid of it.
>> +
>> + return 0;
>> +}
>> +
>> +static int tegra_nand_chips_init(struct device *dev,
>> + struct tegra_nand_controller *ctrl)
>> +{
>> + struct device_node *np = dev->of_node;
>> + struct device_node *np_nand;
>> + int nchips = of_get_child_count(np);
>> + struct tegra_nand_chip *nand;
>> + struct mtd_info *mtd;
>> + struct nand_chip *chip;
>> + unsigned long config, bch_config = 0;
>> + int bits_per_step;
>> + int err;
>> +
>> + if (nchips != 1) {
>> + dev_err(dev, "currently only one NAND chip supported\n");
>> + return -EINVAL;
>> + }
>> +
>> + np_nand = of_get_next_child(np, NULL);
>> +
>> + nand = devm_kzalloc(dev, sizeof(*nand), GFP_KERNEL);
>> + if (!nand) {
>> + dev_err(dev, "could not allocate chip structure\n");
>> + return -ENOMEM;
>> + }
>> +
>> + nand->wp_gpio = devm_gpiod_get_optional(dev, "wp", GPIOD_OUT_LOW);
>> +
>> + if (IS_ERR(nand->wp_gpio)) {
>> + err = PTR_ERR(nand->wp_gpio);
>> + dev_err(dev, "failed to request WP GPIO: %d\n", err);
>> + return err;
>> + }
>> +
>> + chip = &nand->chip;
>> + chip->controller = &ctrl->controller;
>> + ctrl->chip = chip;
>> +
>> + mtd = nand_to_mtd(chip);
>> +
>> + mtd->dev.parent = dev;
>> + mtd->name = "tegra_nand";
>> + mtd->owner = THIS_MODULE;
>> +
>> + nand_set_flash_node(chip, np_nand);
>> +
>> + chip->options = NAND_NO_SUBPAGE_WRITE | NAND_USE_BOUNCE_BUFFER;
>> + chip->exec_op = tegra_nand_exec_op;
>> + chip->select_chip = tegra_nand_select_chip;
>> + chip->setup_data_interface = tegra_nand_setup_data_interface;
>> +
>> + err = nand_scan_ident(mtd, 1, NULL);
>> + if (err)
>> + return err;
>> +
>> + if (chip->bbt_options & NAND_BBT_USE_FLASH)
>> + chip->bbt_options |= NAND_BBT_NO_OOB;
>> +
>> + chip->ecc.mode = NAND_ECC_HW;
>> + if (!chip->ecc.size)
>> + chip->ecc.size = 512;
>> + if (chip->ecc.size != 512)
>> + return -EINVAL;
>
> This is useless. You can force ecc.size to 512 and forget about the DT
> property (please update the DT bindings).
>
Ok.
>> +
>> + chip->ecc.read_page = tegra_nand_read_page_hwecc;
>> + chip->ecc.write_page = tegra_nand_write_page_hwecc;
>> + /* Not functional for unknown reason...
>> + chip->ecc.read_page_raw = tegra_nand_read_page;
>> + chip->ecc.write_page_raw = tegra_nand_write_page;
>
> Please add the _raw suffix to these helpers.
>
They are also used from tegra_nand_read_page_hwecc, that is why I was
hesitant to add _raw...
>> + */
>> + config = readl(ctrl->regs + CFG);
>> + config |= CFG_PIPE_EN | CFG_SKIP_SPARE | CFG_SKIP_SPARE_SIZE_4;
>> +
>> + if (chip->options & NAND_BUSWIDTH_16)
>> + config |= CFG_BUS_WIDTH_16;
>> +
>> + switch (chip->ecc.algo) {
>> + case NAND_ECC_RS:
>> + bits_per_step = BITS_PER_STEP_RS * chip->ecc.strength;
>> + mtd_set_ooblayout(mtd, &tegra_nand_oob_rs_ops);
>> + switch (chip->ecc.strength) {
>> + case 4:
>> + config |= CFG_ECC_SEL | CFG_TVAL_4;
>> + break;
>> + case 6:
>> + config |= CFG_ECC_SEL | CFG_TVAL_6;
>> + break;
>> + case 8:
>> + config |= CFG_ECC_SEL | CFG_TVAL_8;
>> + break;
>> + default:
>> + dev_err(dev, "ECC strength %d not supported\n",
>> + chip->ecc.strength);
>> + return -EINVAL;
>> + }
>> + break;
>> + case NAND_ECC_BCH:
>> + bits_per_step = BITS_PER_STEP_BCH * chip->ecc.strength;
>> + mtd_set_ooblayout(mtd, &tegra_nand_oob_bch_ops);
>> + switch (chip->ecc.strength) {
>> + case 4:
>> + bch_config = BCH_TVAL_4;
>> + break;
>> + case 8:
>> + bch_config = BCH_TVAL_8;
>> + break;
>> + case 14:
>> + bch_config = BCH_TVAL_14;
>> + break;
>> + case 16:
>> + bch_config = BCH_TVAL_16;
>> + break;
>> + default:
>> + dev_err(dev, "ECC strength %d not supported\n",
>> + chip->ecc.strength);
>> + return -EINVAL;
>> + }
>> + break;
>> + default:
>> + dev_err(dev, "ECC algorithm not supported\n");
>> + return -EINVAL;
>> + }
>> +
>> + chip->ecc.bytes = DIV_ROUND_UP(bits_per_step, 8);
>> +
>> + switch (mtd->writesize) {
>> + case 256:
>> + config |= CFG_PS_256;
>> + break;
>> + case 512:
>> + config |= CFG_PS_512;
>> + break;
>> + case 1024:
>> + config |= CFG_PS_1024;
>> + break;
>> + case 2048:
>> + config |= CFG_PS_2048;
>> + break;
>> + case 4096:
>> + config |= CFG_PS_4096;
>> + break;
>> + default:
>> + dev_err(dev, "unhandled writesize %d\n", mtd->writesize);
>> + return -ENODEV;
>> + }
>> +
>> + writel(config, ctrl->regs + CFG);
>> + writel(bch_config, ctrl->regs + BCH_CONFIG);
>> +
>> + err = nand_scan_tail(mtd);
>> + if (err)
>> + return err;
>> +
>> + config |= CFG_TAG_BYTE_SIZE(mtd_ooblayout_count_freebytes(mtd) - 1);
>> + writel(config, ctrl->regs + CFG);
>> +
>> + err = mtd_device_register(mtd, NULL, 0);
>> + if (err)
>
> Missing nand_cleanup() in the error path.
>
Ok.
--
Stefan
>> + return err;
>> +
>> + return 0;
>> +}
>> +
>
> [...]
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