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SubjectRe: [RESEND PATCH 2/5] mtd: rawnand: add NVIDIA Tegra NAND Flash controller driver
On 28.05.2018 00:04, Miquel Raynal wrote:
> Hi Stefan,
>
> I just see your v2 while I'm sending my review on the driver, will
> probably wait for v4 then ;)

Hehe, yeah lets hope we do not race on v3 :-)

Some comments to things which are not addressed yet in v2:

>
> Thanks for the work though!
> Miquèl
>
> On Tue, 22 May 2018 14:07:06 +0200, Stefan Agner <stefan@agner.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@lynxeye.de>
>> Signed-off-by: Stefan Agner <stefan@agner.ch>
>> ---
>
> [...]
>
>> --- /dev/null
>> +++ b/drivers/mtd/nand/raw/tegra_nand.c
>> @@ -0,0 +1,915 @@
>> +/*
>> + * Copyright (C) 2018 Stefan Agner <stefan@agner.ch>
>> + * Copyright (C) 2014-2015 Lucas Stach <dev@lynxeye.de>
>> + * Copyright (C) 2012 Avionic Design GmbH
>> + *
>> + * 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.
>
> Please use SPDX tag.
>
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/completion.h>
>> +#include <linux/delay.h>
>> +#include <linux/dma-mapping.h>
>> +#include <linux/err.h>
>> +#include <linux/gpio/consumer.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/io.h>
>> +#include <linux/module.h>
>> +#include <linux/mtd/partitions.h>
>> +#include <linux/mtd/rawnand.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/reset.h>
>> +
>> +#define CMD 0x00
>> +#define CMD_GO (1 << 31)
>> +#define CMD_CLE (1 << 30)
>> +#define CMD_ALE (1 << 29)
>> +#define CMD_PIO (1 << 28)
>> +#define CMD_TX (1 << 27)
>> +#define CMD_RX (1 << 26)
>
> Please use the BIT(x) macro instead of (1 << x)
>

Ok.

>> +#define CMD_SEC_CMD (1 << 25)
>> +#define CMD_AFT_DAT (1 << 24)
>> +#define CMD_TRANS_SIZE(x) (((x - 1) & 0xf) << 20)
>> +#define CMD_A_VALID (1 << 19)
>> +#define CMD_B_VALID (1 << 18)
>> +#define CMD_RD_STATUS_CHK (1 << 17)
>> +#define CMD_RBSY_CHK (1 << 16)
>> +#define CMD_CE(x) (1 << (8 + ((x) & 0x7)))
>> +#define CMD_CLE_SIZE(x) (((x - 1) & 0x3) << 4)
>> +#define CMD_ALE_SIZE(x) (((x - 1) & 0xf) << 0)
>> +
>
> [...]
>
>> +static int tegra_nand_cmd(struct nand_chip *chip,
>> + const struct nand_subop *subop)
>> +{
>> + const struct nand_op_instr *instr;
>> + const struct nand_op_instr *instr_data_in = NULL;
>> + struct mtd_info *mtd = nand_to_mtd(chip);
>> + struct tegra_nand *nand = to_tegra_nand(mtd);
>> + unsigned int op_id = -1, trfr_in_sz = 0, trfr_out_sz = 0, offset = 0;
>> + bool first_cmd = true;
>> + bool force8bit;
>> + u32 cmd = 0;
>> + u32 value;
>> +
>> + for (op_id = 0; op_id < subop->ninstrs; op_id++) {
>> + unsigned int naddrs, i;
>> + const u8 *addrs;
>> + u32 addr1 = 0, addr2 = 0;
>> +
>> + instr = &subop->instrs[op_id];
>> +
>> + switch (instr->type) {
>> + case NAND_OP_CMD_INSTR:
>> + if (first_cmd) {
>> + cmd |= CMD_CLE;
>> + writel(instr->ctx.cmd.opcode, nand->regs + CMD_1);
>> + } else {
>> + cmd |= CMD_SEC_CMD;
>> + writel(instr->ctx.cmd.opcode, nand->regs + CMD_2);
>> + }
>> + first_cmd = false;
>> + break;
>> + case NAND_OP_ADDR_INSTR:
>> + offset = nand_subop_get_addr_start_off(subop, op_id);
>> + naddrs = nand_subop_get_num_addr_cyc(subop, op_id);
>> + addrs = &instr->ctx.addr.addrs[offset];
>> +
>> + cmd |= CMD_ALE | CMD_ALE_SIZE(naddrs);
>> + for (i = 0; i < min_t(unsigned int, 4, naddrs); i++)
>> + addr1 |= *addrs++ << (8 * i);
>> + naddrs -= i;
>> + for (i = 0; i < min_t(unsigned int, 4, naddrs); i++)
>> + addr2 |= *addrs++ << (8 * i);
>> + writel(addr1, nand->regs + ADDR_1);
>> + writel(addr2, nand->regs + ADDR_2);
>> + break;
>> +
>> + case NAND_OP_DATA_IN_INSTR:
>> + trfr_in_sz = nand_subop_get_data_len(subop, op_id);
>> + offset = nand_subop_get_data_start_off(subop, op_id);
>> +
>> + cmd |= CMD_TRANS_SIZE(trfr_in_sz) | CMD_PIO | CMD_RX | CMD_A_VALID;
>> +
>> + instr_data_in = instr;
>> + break;
>> +
>> + case NAND_OP_DATA_OUT_INSTR:
>> + trfr_out_sz = nand_subop_get_data_len(subop, op_id);
>> + offset = nand_subop_get_data_start_off(subop, op_id);
>> + trfr_out_sz = min_t(size_t, trfr_out_sz, 4);
>> +
>> + cmd |= CMD_TRANS_SIZE(trfr_out_sz) | CMD_PIO | CMD_TX | CMD_A_VALID;
>> +
>> + memcpy(&value, instr->ctx.data.buf.out + offset, trfr_out_sz);
>> + writel(value, nand->regs + RESP);
>> +
>> + break;
>> + case NAND_OP_WAITRDY_INSTR:
>> + cmd |= CMD_RBSY_CHK;
>> + break;
>> +
>> + }
>> + }
>> +
>> +
>> + cmd |= CMD_GO | CMD_CE(nand->cur_chip);
>> + writel(cmd, nand->regs + CMD);
>> + wait_for_completion(&nand->command_complete);
>
> _timeout?
>

Yes, I definitely will do this. One half a second should be fine?

>> +
>> + if (instr_data_in) {
>> + u32 value;
>> + size_t n = min_t(size_t, trfr_in_sz, 4);
>> +
>> + value = readl(nand->regs + RESP);
>> + memcpy(instr_data_in->ctx.data.buf.in + offset, &value, n);
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static const struct nand_op_parser tegra_nand_op_parser = NAND_OP_PARSER(
>> + NAND_OP_PARSER_PATTERN(tegra_nand_cmd,
>> + NAND_OP_PARSER_PAT_CMD_ELEM(true),
>> + NAND_OP_PARSER_PAT_ADDR_ELEM(true, 8),
>> + NAND_OP_PARSER_PAT_CMD_ELEM(true),
>> + NAND_OP_PARSER_PAT_WAITRDY_ELEM(true)),
>> + NAND_OP_PARSER_PATTERN(tegra_nand_cmd,
>> + NAND_OP_PARSER_PAT_DATA_OUT_ELEM(false, 4)),
>> + NAND_OP_PARSER_PATTERN(tegra_nand_cmd,
>> + NAND_OP_PARSER_PAT_CMD_ELEM(true),
>> + NAND_OP_PARSER_PAT_ADDR_ELEM(true, 8),
>> + NAND_OP_PARSER_PAT_CMD_ELEM(true),
>> + NAND_OP_PARSER_PAT_WAITRDY_ELEM(true),
>> + NAND_OP_PARSER_PAT_DATA_IN_ELEM(true, 4)),
>> + );
>> +
>> +static int tegra_nand_exec_op(struct nand_chip *chip,
>> + const struct nand_operation *op,
>> + bool check_only)
>> +{
>> + return nand_op_parser_exec_op(chip, &tegra_nand_op_parser, op,
>> + check_only);
>> +}
>> +static void tegra_nand_select_chip(struct mtd_info *mtd, int chip)
>> +{
>> + struct tegra_nand *nand = to_tegra_nand(mtd);
>> +
>> + nand->cur_chip = chip;
>
> You should probably save the timings configuration and apply them back
> here in case of using different chips.
>

So far multiple chips are not supported, but yes, would need to be done
in that case.

>> +}
>> +
>> +static u32 tegra_nand_fill_address(struct mtd_info *mtd, struct nand_chip *chip,
>> + int page)
>> +{
>> + struct tegra_nand *nand = to_tegra_nand(mtd);
>> +
>> + /* Lower 16-bits are column, always 0 */
>> + writel(page << 16, nand->regs + ADDR_1);
>> +
>> + if (chip->options & NAND_ROW_ADDR_3) {
>> + writel(page >> 16, nand->regs + ADDR_2);
>> + return 5;
>> + }
>> +
>> + return 4;
>> +}
>> +
>> +static int tegra_nand_read_page(struct mtd_info *mtd, struct nand_chip *chip,
>> + uint8_t *buf, int oob_required, int page)
>> +{
>> + struct tegra_nand *nand = to_tegra_nand(mtd);
>> + u32 value, addrs;
>> +
>> + writel(NAND_CMD_READ0, nand->regs + CMD_1);
>> + writel(NAND_CMD_READSTART, nand->regs + CMD_2);
>> +
>> + addrs = tegra_nand_fill_address(mtd, chip, page);
>> +
>> + value = readl(nand->regs + CFG);
>> + value |= CFG_HW_ECC | CFG_ERR_COR;
>> + writel(value, nand->regs + CFG);
>> +
>> + writel(mtd->writesize - 1, nand->regs + DMA_CFG_A);
>> + writel(nand->data_dma, nand->regs + DATA_PTR);
>> +
>> + if (oob_required) {
>> + writel(mtd_ooblayout_count_freebytes(mtd) - 1,
>> + nand->regs + DMA_CFG_B);
>> + writel(nand->oob_dma, nand->regs + TAG_PTR);
>> + } else {
>> + writel(0, nand->regs + DMA_CFG_B);
>> + writel(0, nand->regs + TAG_PTR);
>> + }
>> +
>> + value = DMA_CTRL_GO | DMA_CTRL_IN | DMA_CTRL_PERF_EN |
>> + DMA_CTRL_REUSE | DMA_CTRL_IE_DONE | DMA_CTRL_IS_DONE |
>> + DMA_CTRL_BURST_8 | DMA_CTRL_EN_A;
>> + if (oob_required)
>> + value |= DMA_CTRL_EN_B;
>> + writel(value, nand->regs + DMA_CTRL);
>> +
>> + value = CMD_CLE | CMD_ALE | CMD_ALE_SIZE(addrs) | CMD_SEC_CMD |
>> + CMD_RBSY_CHK | CMD_GO | CMD_RX | CMD_TRANS_SIZE(9) |
>> + CMD_A_VALID | CMD_CE(nand->cur_chip);
>> + if (oob_required)
>> + value |= CMD_B_VALID;
>> + writel(value, nand->regs + CMD);
>> +
>> + wait_for_completion(&nand->command_complete);
>> + wait_for_completion(&nand->dma_complete);
>> +
>> + if (oob_required) {
>> + struct mtd_oob_region oobregion;
>> +
>> + mtd_ooblayout_free(mtd, 0, &oobregion);
>
> Don't you want to save the oobregion parameters once and then just
> refer to them?
>

I probably could just safe the size of the free OOB region.

Anyway have some open questions wrt OOB support with HW ECC, see cover
letter of v2.

>> + memcpy(chip->oob_poi, nand->oob_buf + oobregion.offset,
>> + mtd_ooblayout_count_freebytes(mtd));
>> + }
>> + memcpy(buf, nand->data_buf, mtd->writesize);
>> +
>> + value = readl(nand->regs + CFG);
>> + value &= ~(CFG_HW_ECC | CFG_ERR_COR);
>> + writel(value, nand->regs + CFG);
>> +
>> + value = readl(nand->regs + DEC_STATUS);
>> + if (value & DEC_STATUS_A_ECC_FAIL) {
>> + /*
>> + * The ECC isn't smart enough to figure out if a page is
>> + * completely erased and flags an error in this case. So we
>> + * check the read data here to figure out if it's a legitimate
>> + * error or a false positive.
>> + */
>> + int i, err;
>> + int flips_threshold = chip->ecc.strength / 2;
>> + int max_bitflips = 0;
>> +
>> + for (i = 0; i < chip->ecc.steps; i++) {
>> + u8 *data = buf + (chip->ecc.size * i);
>> + err = nand_check_erased_ecc_chunk(data, chip->ecc.size,
>
> Are you sure the data was uncorrected there? I bet you have corrected
> data in chip->ecc.size and should re-read the page with the raw
> helpers before using nand_check_erased_ecc_chunk().
>

Hm, quite likely. Will check that.

>> + NULL, 0,
>> + NULL, 0,
>> + flips_threshold);
>
> I think you should use chip->ecc.strength instead of flips_threshold
> (and remove it).
>

Hm, so higher level will check and relocate if we get closer to
correctable bits?

Probably wrong in drivers/mtd/nand/raw/vf610_nfc.c then too?

>> + if (err < 0)
>> + return err;
>
> In case of ECC failure you should increment ecc_stats.failed.
>
>> +
>> + max_bitflips += max_bitflips;
>
> max_bitflipts = max_t(unsigned int, max_bitflipts, err);
>
>> + }
>> +
>> + return max_bitflips;
>> + }
>> +
>> + if (nand->last_read_error) {
>> + int max_corr_cnt, corr_sec_flag;
>> +
>> + value = readl(nand->regs + DEC_STAT_BUF);
>> + corr_sec_flag = (value & DEC_STAT_BUF_CORR_SEC_FLAG_MASK) >>
>> + DEC_STAT_BUF_CORR_SEC_FLAG_SHIFT;
>> + max_corr_cnt = (value & DEC_STAT_BUF_MAX_CORR_CNT_MASK) >>
>> + DEC_STAT_BUF_MAX_CORR_CNT_SHIFT;
>> +
>> + /*
>> + * The value returned in the register is the maximum of
>> + * bitflips encountered in any of the ECC regions. As there is
>> + * no way to get the number of bitflips in a specific regions
>> + * we are not able to deliver correct stats but instead
>> + * overestimate the number of corrected bitflips by assuming
>> + * that all regions where errors have been corrected
>> + * encountered the maximum number of bitflips.
>> + */
>> + mtd->ecc_stats.corrected += max_corr_cnt * hweight8(corr_sec_flag);
>
> That's bad. But okay if we don't have the information.
>
>> + nand->last_read_error = false;
>> + return value;
>> + }
>> +
>> + return 0;
>> +}
>> +
>> +static int tegra_nand_write_page(struct mtd_info *mtd, struct nand_chip *chip,
>> + const uint8_t *buf, int oob_required, int page)
>> +{
>> + struct tegra_nand *nand = to_tegra_nand(mtd);
>> + u32 value, addrs;
>> +
>> + writel(NAND_CMD_SEQIN, nand->regs + CMD_1);
>> + writel(NAND_CMD_PAGEPROG, nand->regs + CMD_2);
>> +
>> + addrs = tegra_nand_fill_address(mtd, chip, page);
>> +
>> + value = readl(nand->regs + CFG);
>> + value |= CFG_HW_ECC | CFG_ERR_COR;
>> + writel(value, nand->regs + CFG);
>
> You might want to test with the _relaxed() operators?
>
>> +
>> + memcpy(nand->data_buf, buf, mtd->writesize);
>> +
>> + writel(mtd->writesize - 1, nand->regs + DMA_CFG_A);
>> + writel(nand->data_dma, nand->regs + DATA_PTR);
>> +
>> + if (oob_required) {
>> + struct mtd_oob_region oobregion;
>> +
>> + mtd_ooblayout_free(mtd, 0, &oobregion);
>> + memcpy(nand->oob_buf, chip->oob_poi + oobregion.offset,
>> + mtd_ooblayout_count_freebytes(mtd));
>> + writel(mtd_ooblayout_count_freebytes(mtd) - 1,
>> + nand->regs + DMA_CFG_B);
>> + writel(nand->oob_dma, nand->regs + TAG_PTR);
>> + } else {
>> + writel(0, nand->regs + DMA_CFG_B);
>> + writel(0, nand->regs + TAG_PTR);
>> + }
>> +
>> + value = DMA_CTRL_GO | DMA_CTRL_OUT | DMA_CTRL_PERF_EN |
>> + DMA_CTRL_IE_DONE | DMA_CTRL_IS_DONE |
>> + DMA_CTRL_BURST_8 | DMA_CTRL_EN_A;
>> + if (oob_required)
>> + value |= DMA_CTRL_EN_B;
>
> Line here
>
>> + writel(value, nand->regs + DMA_CTRL);
>> +
>> + value = CMD_CLE | CMD_ALE | CMD_ALE_SIZE(addrs) | CMD_SEC_CMD |
>> + CMD_AFT_DAT | CMD_RBSY_CHK | CMD_GO | CMD_TX | CMD_A_VALID |
>> + CMD_TRANS_SIZE(9) | CMD_CE(nand->cur_chip);
>> + if (oob_required)
>> + value |= CMD_B_VALID;
>
> Line here
>
>> + writel(value, nand->regs + CMD);
>> +
>> + wait_for_completion(&nand->command_complete);
>> + wait_for_completion(&nand->dma_complete);
>> +
>> + value = readl(nand->regs + CFG);
>> + value &= ~(CFG_HW_ECC | CFG_ERR_COR);
>> + writel(value, nand->regs + CFG);
>> +
>> + return 0;
>> +}
>> +
>> +static void tegra_nand_setup_timing(struct tegra_nand *nand, int mode)
>> +{
>> + /*
>> + * The period (and all other timings in this function) is in ps,
>> + * so need to take care here to avoid integer overflows.
>
> You might wanna check __DIVIDE, PSEC_TO_NSEC and PSEC_TO_MSEC macros in
> rawnand.h. You could use them in the following derivations.
>
>> + */
>> + unsigned int rate = clk_get_rate(nand->clk) / 1000000;
>> + unsigned int period = DIV_ROUND_UP(1000000, rate);
>> + const struct nand_sdr_timings *timings;
>> + u32 val, reg = 0;
>> +
>> + timings = onfi_async_timing_mode_to_sdr_timings(mode);
>> +
>> + val = DIV_ROUND_UP(max3(timings->tAR_min, timings->tRR_min,
>> + timings->tRC_min), period);
>> + if (val > 2)
>> + val -= 3;
>> + reg |= TIMING_TCR_TAR_TRR(val);
>> +
>> + val = DIV_ROUND_UP(max(max(timings->tCS_min, timings->tCH_min),
>> + max(timings->tALS_min, timings->tALH_min)),
>
> Is the second line aligned correctly?
>
>> + period);
>> + if (val > 1)
>> + val -= 2;
>
> This is weird and I would recommend a comment.
>
>> + reg |= TIMING_TCS(val);
>> +
>> + val = DIV_ROUND_UP(max(timings->tRP_min, timings->tREA_max) + 6000,
>> + period);
>> + reg |= TIMING_TRP(val) | TIMING_TRP_RESP(val);
>> +
>> + reg |= TIMING_TWB(DIV_ROUND_UP(timings->tWB_max, period));
>> + reg |= TIMING_TWHR(DIV_ROUND_UP(timings->tWHR_min, period));
>> + reg |= TIMING_TWH(DIV_ROUND_UP(timings->tWH_min, period));
>> + reg |= TIMING_TWP(DIV_ROUND_UP(timings->tWP_min, period));
>> + reg |= TIMING_TRH(DIV_ROUND_UP(timings->tRHW_min, period));
>> +
>> + writel(reg, nand->regs + TIMING_1);
>> +
>> + val = DIV_ROUND_UP(timings->tADL_min, period);
>> + if (val > 2)
>> + val -= 3;
>
> Ditto
>
>> + reg = TIMING_TADL(val);
>> +
>> + writel(reg, nand->regs + TIMING_2);
>> +}
>> +
>> +static void tegra_nand_setup_chiptiming(struct tegra_nand *nand)
>> +{
>> + struct nand_chip *chip = &nand->chip;
>> + int mode;
>> +
>> + mode = onfi_get_async_timing_mode(chip);
>> + if (mode == ONFI_TIMING_MODE_UNKNOWN)
>> + mode = chip->onfi_timing_mode_default;
>> + else
>> + mode = fls(mode);
>> +
>> + tegra_nand_setup_timing(nand, mode);
>> +}
>
> You can drop this function and use tegra_nand_setup_timing directly as
> hook for ->setup_data_interface().
>
>> +
>> +static int tegra_nand_probe(struct platform_device *pdev)
>> +{
>> + struct reset_control *rst;
>> + struct tegra_nand *nand;
>
> Would you mind having another name for the tegra_nand structure than
> just 'nand'? I found it confusing as, following Boris comment, it won't
> be a 'NAND device' structure but rather more a controller structure.
>
>> + struct nand_chip *chip;
>> + struct mtd_info *mtd;
>> + struct resource *res;
>> + unsigned long value;
>
> s/value/reg/ ? or something more explicit?
>
>> + int irq, err = 0;
>> +
>> + nand = devm_kzalloc(&pdev->dev, sizeof(*nand), GFP_KERNEL);
>> + if (!nand)
>> + return -ENOMEM;
>> +
>> + nand->dev = &pdev->dev;
>> +
>> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> + nand->regs = devm_ioremap_resource(&pdev->dev, res);
>> + if (IS_ERR(nand->regs))
>> + return PTR_ERR(nand->regs);
>> +
>> + irq = platform_get_irq(pdev, 0);
>> + err = devm_request_irq(&pdev->dev, irq, tegra_nand_irq, 0,
>> + dev_name(&pdev->dev), nand);
>> + if (err)
>> + return err;
>> +
>> + rst = devm_reset_control_get(&pdev->dev, "nand");
>> + if (IS_ERR(rst))
>> + return PTR_ERR(rst);
>> +
>> + nand->clk = devm_clk_get(&pdev->dev, "nand");
>> + if (IS_ERR(nand->clk))
>> + return PTR_ERR(nand->clk);
>> +
>> + nand->wp_gpio = gpiod_get_optional(&pdev->dev, "wp-gpios",
>> + GPIOD_OUT_HIGH);
>> + if (IS_ERR(nand->wp_gpio))
>> + return PTR_ERR(nand->wp_gpio);
>> +
>> + err = clk_prepare_enable(nand->clk);
>> + if (err)
>> + return err;
>> +
>> + reset_control_assert(rst);
>> + udelay(2);
>> + reset_control_deassert(rst);
>> +
>> + value = HWSTATUS_RDSTATUS_MASK(1) | HWSTATUS_RDSTATUS_VALUE(0) |
>> + HWSTATUS_RBSY_MASK(NAND_STATUS_READY) |
>> + HWSTATUS_RBSY_VALUE(NAND_STATUS_READY);
>> + writel(NAND_CMD_STATUS, nand->regs + HWSTATUS_CMD);
>> + writel(value, nand->regs + HWSTATUS_MASK);
>> +
>> + init_completion(&nand->command_complete);
>> + init_completion(&nand->dma_complete);
>> +
>> + /* clear interrupts */
>> + value = readl(nand->regs + ISR);
>> + writel(value, nand->regs + ISR);
>> +
>> + writel(DMA_CTRL_IS_DONE, nand->regs + DMA_CTRL);
>> +
>> + /* enable interrupts */
>> + value = IER_UND | IER_OVR | IER_CMD_DONE | IER_ECC_ERR | IER_GIE;
>> + writel(value, nand->regs + IER);
>> +
>> + /* reset config */
>> + writel(0, nand->regs + CFG);
>> +
>> + chip = &nand->chip;
>> + mtd = nand_to_mtd(chip);
>> +
>> + mtd->dev.parent = &pdev->dev;
>> + mtd->name = "tegra_nand";
>
> I just figured it was undocumented (yet) but you could have a label
> string property in your nand DT node that tells you the name of the
> MTD device instead of something too generic like tegra_nand.
>

I think that was used back in the kernel parameter mtd partition time?
So maybe it should stay the same in case somebody uses it? But yeah, I
can use a label property with "tegra_nand" instead of hard coding it.

--
Stefan

>> + mtd->owner = THIS_MODULE;
>> +
>> + nand_set_flash_node(chip, pdev->dev.of_node);
>> + nand_set_controller_data(chip, nand);
>> +
>> + chip->options = NAND_NO_SUBPAGE_WRITE;
>> + chip->exec_op = tegra_nand_exec_op;
>> + chip->select_chip = tegra_nand_select_chip;
>> + tegra_nand_setup_timing(nand, 0);
>
> You really should implement ->setup_data_interface() and let the core
> handle the timings issue entirely (mind that chipnr is not the NAND
> chip id but more the CS id asserted for the pointed NAND chip).
>
>> +
>> + err = nand_scan_ident(mtd, 1, NULL);
>> + if (err)
>> + goto err_disable_clk;
>> +
>> + if (chip->bbt_options & NAND_BBT_USE_FLASH)
>> + chip->bbt_options |= NAND_BBT_NO_OOB;
>> +
>> + nand->data_buf = dmam_alloc_coherent(&pdev->dev, mtd->writesize,
>> + &nand->data_dma, GFP_KERNEL);
>
> Do you need these buffers before nand_scan_tail() or could you simply
> use the ones allocated by the core right after?
>
>> + if (!nand->data_buf) {
>> + err = -ENOMEM;
>> + goto err_disable_clk;
>> + }
>> +
>> + nand->oob_buf = dmam_alloc_coherent(&pdev->dev, mtd->oobsize,
>> + &nand->oob_dma, GFP_KERNEL);
>> + if (!nand->oob_buf) {
>> + err = -ENOMEM;
>> + goto err_disable_clk;
>> + }
>> +
>> + chip->ecc.mode = NAND_ECC_HW;
>> + chip->ecc.size = 512;
>> + chip->ecc.read_page = tegra_nand_read_page;
>> + chip->ecc.write_page = tegra_nand_write_page;
>> +
>> + value = readl(nand->regs + CFG);
>> + value |= CFG_PIPE_EN | CFG_SKIP_SPARE | CFG_SKIP_SPARE_SIZE_4 |
>> + CFG_TAG_BYTE_SIZE(mtd_ooblayout_count_freebytes(mtd) - 1);
>> +
>> + if (chip->options & NAND_BUSWIDTH_16)
>> + value |= CFG_BUS_WIDTH_16;
>> +
>> + switch (mtd->oobsize) {
>> + case 16:
>> + mtd_set_ooblayout(mtd, &tegra_nand_oob_16_ops);
>> + chip->ecc.strength = 1;
>> + chip->ecc.bytes = 4;
>> + break;
>> + case 64:
>> + mtd_set_ooblayout(mtd, &tegra_nand_oob_64_ops);
>> + chip->ecc.strength = 8;
>> + chip->ecc.bytes = 18;
>> + value |= CFG_ECC_SEL | CFG_TVAL_8;
>> + break;
>> + case 128:
>> + mtd_set_ooblayout(mtd, &tegra_nand_oob_128_ops);
>> + chip->ecc.strength = 8;
>> + chip->ecc.bytes = 18;
>> + value |= CFG_ECC_SEL | CFG_TVAL_8;
>> + break;
>> + case 224:
>> + mtd_set_ooblayout(mtd, &tegra_nand_oob_224_ops);
>> + chip->ecc.strength = 8;
>> + chip->ecc.bytes = 18;
>> + value |= CFG_ECC_SEL | CFG_TVAL_8;
>> + break;
>> + default:
>> + dev_err(&pdev->dev, "unhandled OOB size %d\n", mtd->oobsize);
>> + err = -ENODEV;
>> + goto err_disable_clk;
>> + }
>> +
>> + switch (mtd->writesize) {
>> + case 256:
>> + value |= CFG_PS_256;
>> + break;
>> + case 512:
>> + value |= CFG_PS_512;
>> + break;
>> + case 1024:
>> + value |= CFG_PS_1024;
>> + break;
>> + case 2048:
>> + value |= CFG_PS_2048;
>> + break;
>> + case 4096:
>> + value |= CFG_PS_4096;
>> + break;
>> + default:
>> + dev_err(&pdev->dev, "unhandled writesize %d\n", mtd->writesize);
>> + err = -ENODEV;
>> + goto err_disable_clk;
>> + }
>> +
>> + writel(value, nand->regs + CFG);
>> +
>> + tegra_nand_setup_chiptiming(nand);
>> +
>> + err = nand_scan_tail(mtd);
>> + if (err)
>> + goto err_disable_clk;
>> +
>> + err = mtd_device_register(mtd, NULL, 0);
>> + if (err)
>> + goto err_cleanup_nand;
>> +
>> + platform_set_drvdata(pdev, nand);
>> +
>> + return 0;
>> +
>> +err_cleanup_nand:
>> + nand_cleanup(chip);
>> +err_disable_clk:
>> + clk_disable_unprepare(nand->clk);
>> + return err;
>> +}
>> +
>> +static int tegra_nand_remove(struct platform_device *pdev)
>> +{
>> + struct tegra_nand *nand = platform_get_drvdata(pdev);
>> +
>> + nand_release(nand_to_mtd(&nand->chip));
>> +
>> + clk_disable_unprepare(nand->clk);
>> +
>> + return 0;
>> +}
>> +
>> +static const struct of_device_id tegra_nand_of_match[] = {
>> + { .compatible = "nvidia,tegra20-nand" },
>> + { /* sentinel */ }
>> +};
>> +
>> +static struct platform_driver tegra_nand_driver = {
>> + .driver = {
>> + .name = "tegra-nand",
>> + .of_match_table = tegra_nand_of_match,
>> + },
>> + .probe = tegra_nand_probe,
>> + .remove = tegra_nand_remove,
>> +};
>> +module_platform_driver(tegra_nand_driver);
>> +
>> +MODULE_DESCRIPTION("NVIDIA Tegra NAND driver");
>> +MODULE_AUTHOR("Thierry Reding <thierry.reding@nvidia.com>");
>> +MODULE_AUTHOR("Lucas Stach <dev@lynxeye.de>");
>> +MODULE_AUTHOR("Stefan Agner <stefan@agner.ch>");
>> +MODULE_LICENSE("GPL v2");
>> +MODULE_DEVICE_TABLE(of, tegra_nand_of_match);

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