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Date:   Mon, 7 Sep 2020 15:20:25 +0200
From:   Miquel Raynal <miquel.raynal@bootlin.com>
To:     "Ramuthevar,Vadivel MuruganX" 
        <vadivel.muruganx.ramuthevar@linux.intel.com>
Cc:     linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org,
        devicetree@vger.kernel.org, richard@nod.at, vigneshr@ti.com,
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        boris.brezillon@collabora.com, anders.roxell@linaro.org,
        masonccyang@mxic.com.tw, robh+dt@kernel.org,
        linux-mips@vger.kernel.org, hauke.mehrtens@intel.com,
        andriy.shevchenko@intel.com, cheol.yong.kim@intel.com,
        qi-ming.wu@intel.com
Subject: Re: [RESEND PATCH v12 2/2] mtd: rawnand: Add NAND controller
 support on Intel LGM SoC
Message-ID: <20200907152025.66c18f5e@xps13>
In-Reply-To: <20200817052709.47035-3-vadivel.muruganx.ramuthevar@linux.intel.com>
References: <20200817052709.47035-1-vadivel.muruganx.ramuthevar@linux.intel.com>
        <20200817052709.47035-3-vadivel.muruganx.ramuthevar@linux.intel.com>
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Hi Murugan,

A few more comments below, but I guess the driver looks better now.

> +struct ebu_nand_controller {
> +	struct nand_controller controller;
> +	struct nand_chip chip;
> +	struct device *dev;
> +	void __iomem *ebu;
> +	void __iomem *hsnand;
> +	struct dma_chan *dma_tx;
> +	struct dma_chan *dma_rx;
> +	struct completion dma_access_complete;
> +	unsigned long clk_rate;
> +	struct clk *clk;
> +	u32 nd_para0;
> +	u8 cs_num;
> +	struct ebu_nand_cs cs[MAX_CS];
> +};
> +
> +static inline struct ebu_nand_controller *nand_to_ebu(struct nand_chip *chip)
> +{
> +	return container_of(chip, struct ebu_nand_controller, chip);
> +}
> +
> +static u8 ebu_nand_readb(struct nand_chip *chip)

Can't you prefix with intel_ instead of ebu_ ?

> +{
> +	struct ebu_nand_controller *ebu_host = nand_get_controller_data(chip);
> +	void __iomem *nand_wait = ebu_host->ebu + EBU_WAIT;
> +	u8 cs_num = ebu_host->cs_num;
> +	u32 stat;
> +	int ret;
> +	u8 val;
> +
> +	val = readb(ebu_host->cs[cs_num].chipaddr + HSNAND_CS_OFFS);
> +
> +	ret = readl_poll_timeout(nand_wait, stat, stat & EBU_WAIT_WR_C,
> +				 20, 1000);

If you do this operation each time a byte is read/written, you probable
want to shrink the polling delay a little bit, to 1 or even 0.

> +	if (ret)
> +		dev_warn(ebu_host->dev,
> +			 "ebu nand write timeout. nand_wait(0x%p)=0x%x\n",
> +			 nand_wait, readl(nand_wait));
> +
> +	return val;

You should not return val if ret is !0 I guess

> +}
> +
> +static void ebu_nand_writeb(struct nand_chip *chip, u32 offset, u8 value)
> +{
> +	struct ebu_nand_controller *ebu_host = nand_get_controller_data(chip);
> +	void __iomem *nand_wait = ebu_host->ebu + EBU_WAIT;
> +	u8 cs_num = ebu_host->cs_num;
> +	u32 stat;
> +	int ret;
> +
> +	writeb(value, ebu_host->cs[cs_num].chipaddr + offset);
> +
> +	ret = readl_poll_timeout(nand_wait, stat, stat & EBU_WAIT_WR_C,
> +				 20, 1000);

Here as well

> +	if (ret)
> +		dev_warn(ebu_host->dev,
> +			 "ebu nand write timeout. nand_wait(0x%p)=0x%x\n",
> +			 nand_wait, readl(nand_wait));

If this can fail, then the helper should return an error and be treated.

> +}
> +
> +static void ebu_read_buf(struct nand_chip *chip, u_char *buf, unsigned int len)
> +{
> +	int i;
> +
> +	for (i = 0; i < len; i++)
> +		buf[i] = ebu_nand_readb(chip);
> +}
> +
> +static void ebu_write_buf(struct nand_chip *chip, const u_char *buf, int len)
> +{
> +	int i;
> +
> +	for (i = 0; i < len; i++)
> +		ebu_nand_writeb(chip, HSNAND_CS_OFFS, buf[i]);
> +}
> +
> +static void ebu_nand_disable(struct nand_chip *chip)
> +{
> +	struct ebu_nand_controller *ebu_host = nand_get_controller_data(chip);
> +
> +	writel(0, ebu_host->ebu + EBU_CON);
> +}
> +
> +static void ebu_select_chip(struct nand_chip *chip)
> +{
> +	struct ebu_nand_controller *ebu_host = nand_get_controller_data(chip);
> +	void __iomem *nand_con = ebu_host->ebu + EBU_CON;
> +	u32 cs = ebu_host->cs_num;
> +
> +	writel(EBU_CON_NANDM_EN | EBU_CON_CSMUX_E_EN | EBU_CON_CS_P_LOW |
> +	       EBU_CON_SE_P_LOW | EBU_CON_WP_P_LOW | EBU_CON_PRE_P_LOW |
> +	       EBU_CON_IN_CS_S(cs) | EBU_CON_OUT_CS_S(cs) |
> +	       EBU_CON_LAT_EN_CS_P, nand_con);
> +}
> +
> +static void ebu_nand_setup_timing(struct ebu_nand_controller *ctrl,
> +				  const struct nand_sdr_timings *timings)
> +{
> +	unsigned int rate = clk_get_rate(ctrl->clk) / 1000000;
> +	unsigned int period = DIV_ROUND_UP(1000000, rate);
> +	u32 trecov, thold, twrwait, trdwait;
> +	u32 reg = 0;
> +
> +	trecov = DIV_ROUND_UP(max(timings->tREA_max, timings->tREH_min),
> +			      period);
> +	reg |= EBU_BUSCON_RECOVC(trecov);
> +
> +	thold = DIV_ROUND_UP(max(timings->tDH_min, timings->tDS_min), period);
> +	reg |= EBU_BUSCON_HOLDC(thold);
> +
> +	trdwait = DIV_ROUND_UP(max(timings->tRC_min, timings->tREH_min),
> +			       period);
> +	reg |= EBU_BUSCON_WAITRDC(trdwait);
> +
> +	twrwait = DIV_ROUND_UP(max(timings->tWC_min, timings->tWH_min), period);
> +	reg |= EBU_BUSCON_WAITWRC(twrwait);
> +
> +	reg |= EBU_BUSCON_CMULT_V4 | EBU_BUSCON_BCGEN_CS | EBU_BUSCON_ALEC |
> +		EBU_BUSCON_SETUP_EN;
> +
> +	writel(reg, ctrl->ebu + EBU_BUSCON(ctrl->cs_num));
> +}
> +
> +static int ebu_nand_setup_data_interface(struct nand_chip *chip, int csline,
> +					 const struct nand_data_interface *conf)

I recently changed the naming around the data interface, please
have a look at the recent commits and update the namings here as
well.

> +{
> +	struct ebu_nand_controller *ctrl = nand_to_ebu(chip);
> +	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;
> +
> +	ebu_nand_setup_timing(ctrl, timings);
> +
> +	return 0;
> +}
> +
> +static int ebu_nand_ooblayout_ecc(struct mtd_info *mtd, int section,
> +				  struct mtd_oob_region *oobregion)
> +{
> +	struct nand_chip *chip = mtd_to_nand(mtd);
> +
> +	if (section)
> +		return -ERANGE;
> +
> +	oobregion->offset = HSNAND_ECC_OFFSET;
> +	oobregion->length = chip->ecc.total;
> +
> +	return 0;
> +}
> +
> +static int ebu_nand_ooblayout_free(struct mtd_info *mtd, int section,
> +				   struct mtd_oob_region *oobregion)
> +{
> +	struct nand_chip *chip = mtd_to_nand(mtd);
> +
> +	if (section)
> +		return -ERANGE;
> +
> +	oobregion->offset = chip->ecc.total + HSNAND_ECC_OFFSET;
> +	oobregion->length = mtd->oobsize - oobregion->offset;
> +
> +	return 0;
> +}
> +
> +static const struct mtd_ooblayout_ops ebu_nand_ooblayout_ops = {
> +	.ecc = ebu_nand_ooblayout_ecc,
> +	.free = ebu_nand_ooblayout_free,
> +};
> +
> +static void ebu_dma_rx_callback(void *cookie)
> +{
> +	struct ebu_nand_controller *ebu_host = cookie;
> +
> +	dmaengine_terminate_async(ebu_host->dma_rx);
> +
> +	complete(&ebu_host->dma_access_complete);
> +}
> +
> +static void ebu_dma_tx_callback(void *cookie)
> +{
> +	struct ebu_nand_controller *ebu_host = cookie;
> +
> +	dmaengine_terminate_async(ebu_host->dma_tx);
> +
> +	complete(&ebu_host->dma_access_complete);
> +}
> +
> +static int ebu_dma_start(struct ebu_nand_controller *ebu_host, u32 dir,
> +			 const u8 *buf, u32 len)
> +{
> +	struct dma_async_tx_descriptor *tx;
> +	struct completion *dma_completion;
> +	dma_async_tx_callback callback;
> +	struct dma_chan *chan;
> +	dma_cookie_t cookie;
> +	unsigned long flags = DMA_CTRL_ACK | DMA_PREP_INTERRUPT;
> +	dma_addr_t buf_dma;
> +	int ret;
> +	u32 timeout;
> +
> +	if (dir == DMA_DEV_TO_MEM) {
> +		chan = ebu_host->dma_rx;
> +		dma_completion = &ebu_host->dma_access_complete;
> +		callback = ebu_dma_rx_callback;
> +	} else {
> +		chan = ebu_host->dma_tx;
> +		dma_completion = &ebu_host->dma_access_complete;
> +		callback = ebu_dma_tx_callback;
> +	}
> +
> +	buf_dma = dma_map_single(chan->device->dev, (void *)buf, len, dir);
> +	if (dma_mapping_error(chan->device->dev, buf_dma)) {
> +		dev_err(ebu_host->dev, "Failed to map DMA buffer\n");
> +		ret = -EIO;
> +		goto err_unmap;
> +	}
> +
> +	tx = dmaengine_prep_slave_single(chan, buf_dma, len, dir, flags);
> +	if (!tx)
> +		return -ENXIO;
> +
> +	tx->callback = callback;
> +	tx->callback_param = ebu_host;
> +	cookie = tx->tx_submit(tx);
> +
> +	ret = dma_submit_error(cookie);
> +	if (ret) {
> +		dev_err(ebu_host->dev, "dma_submit_error %d\n", cookie);
> +		ret = -EIO;
> +		goto err_unmap;
> +	}
> +
> +	init_completion(dma_completion);
> +	dma_async_issue_pending(chan);
> +
> +	/* Wait DMA to finish the data transfer.*/
> +	timeout =

Don't break the line here

> +	wait_for_completion_timeout(dma_completion, msecs_to_jiffies(1000));
> +	if (!timeout) {
> +		dev_err(ebu_host->dev, "I/O Error in DMA RX (status %d)\n",
> +			dmaengine_tx_status(chan, cookie, NULL));
> +		dmaengine_terminate_sync(chan);
> +		ret = -ETIMEDOUT;
> +		goto err_unmap;
> +	}
> +
> +	return 0;
> +
> +err_unmap:
> +	dma_unmap_single(ebu_host->dev, buf_dma, len, dir);
> +
> +	return ret;
> +}
> +
> +static void ebu_nand_trigger(struct ebu_nand_controller *ebu_host,
> +			     int page, u32 cmd)
> +{
> +	unsigned int val;
> +
> +	val = cmd | (page & 0xFF) << HSNAND_CTL1_ADDR_SHIFT;
> +	writel(val, ebu_host->hsnand + HSNAND_CTL1);
> +	val = (page & 0xFFFF00) >> 8 | HSNAND_CTL2_CYC_N_V5;
> +	writel(val, ebu_host->hsnand + HSNAND_CTL2);
> +
> +	writel(ebu_host->nd_para0, ebu_host->hsnand + HSNAND_PARA0);
> +
> +	/* clear first, will update later */
> +	writel(0xFFFFFFFF, ebu_host->hsnand + HSNAND_CMSG_0);
> +	writel(0xFFFFFFFF, ebu_host->hsnand + HSNAND_CMSG_1);
> +
> +	writel(HSNAND_INT_MSK_CTL_WR_C,
> +	       ebu_host->hsnand + HSNAND_INT_MSK_CTL);
> +
> +	val = cmd == NAND_CMD_READ0 ? HSNAND_CTL_RW_READ : HSNAND_CTL_RW_WRITE;

I don't like this, prefer having a "read/write" boolean as a parameter.

> +
> +	writel(HSNAND_CTL_MSG_EN | HSNAND_CTL_CKFF_EN |
> +	       HSNAND_CTL_ECC_OFF_V8TH | HSNAND_CTL_CE_SEL_CS(ebu_host->cs_num) |
> +	       HSNAND_CTL_ENABLE_ECC | HSNAND_CTL_GO | val,
> +	       ebu_host->hsnand + HSNAND_CTL);
> +}
> +
> +static int ebu_nand_read_page_hwecc(struct nand_chip *chip, u8 *buf,
> +				    int oob_required, int page)
> +{
> +	struct mtd_info *mtd = nand_to_mtd(chip);
> +	struct ebu_nand_controller *ebu_host = nand_get_controller_data(chip);
> +	int ret, x;
> +
> +	ebu_nand_trigger(ebu_host, page, NAND_CMD_READ0);
> +
> +	ret = ebu_dma_start(ebu_host, DMA_DEV_TO_MEM, buf, mtd->writesize);
> +	if (ret)
> +		return ret;
> +
> +	if (oob_required)
> +		chip->ecc.read_oob(chip, page);
> +
> +	x = readl(ebu_host->hsnand + HSNAND_CTL);
> +	x &= ~HSNAND_CTL_GO;
> +	writel(x, ebu_host->hsnand + HSNAND_CTL);
> +
> +	return 0;
> +}
> +
> +static int ebu_nand_write_page_hwecc(struct nand_chip *chip, const u8 *buf,
> +				     int oob_required, int page)
> +{
> +	struct mtd_info *mtd = nand_to_mtd(chip);
> +	struct ebu_nand_controller *ebu_host = nand_get_controller_data(chip);
> +	void __iomem *int_sta = ebu_host->hsnand + HSNAND_INT_STA;
> +	int ret, val, x;
> +	u32 reg;
> +
> +	ebu_nand_trigger(ebu_host, page, NAND_CMD_SEQIN);
> +
> +	ret = ebu_dma_start(ebu_host, DMA_MEM_TO_DEV, buf, mtd->writesize);
> +	if (ret)
> +		return ret;
> +
> +	if (oob_required) {
> +		reg = (chip->oob_poi[3] << 24) | (chip->oob_poi[2] << 16) |
> +			(chip->oob_poi[1] << 8) | chip->oob_poi[0];
> +
> +		writel(reg, ebu_host->hsnand + HSNAND_CMSG_0);
> +
> +		reg = (chip->oob_poi[7] << 24) | (chip->oob_poi[6] << 16) |
> +			(chip->oob_poi[5] << 8) | chip->oob_poi[4];
> +
> +		writel(reg, ebu_host->hsnand + HSNAND_CMSG_1);
> +	}
> +
> +	ret = readl_poll_timeout_atomic(int_sta, val,
> +					!(val & HSNAND_INT_STA_WR_C), 10, 1000);
> +	if (ret)
> +		return -EIO;

return ret ?

> +
> +	x = readl(ebu_host->hsnand + HSNAND_CTL);
> +	x &= ~HSNAND_CTL_GO;
> +	writel(x, ebu_host->hsnand + HSNAND_CTL);

What is this? Looks like it deserves a helper with a nice name.

> +
> +	return 0;
> +}
> +
> +static const u8 ecc_strength[] = { 1, 1, 4, 8, 24, 32, 40, 60, };

                                         ^ is this normal?

> +
> +static int ebu_nand_attach_chip(struct nand_chip *chip)
> +{
> +	struct mtd_info *mtd = nand_to_mtd(chip);
> +	struct ebu_nand_controller *ebu_host = nand_get_controller_data(chip);
> +	u32 ecc_steps, ecc_bytes, ecc_total, pagesize, pg_per_blk;
> +	u32 ecc_strength_ds = chip->ecc.strength;
> +	u32 ecc_size = chip->ecc.size;
> +	u32 writesize = mtd->writesize;
> +	u32 blocksize = mtd->erasesize;
> +	int bch_algo, start, val;
> +
> +	if (chip->ecc.mode != NAND_ECC_HW)
> +		return 0;
> +
> +	/* Default to an ECC size of 512 */
> +	if (!chip->ecc.size)
> +		chip->ecc.size = 512;
> +
> +	switch (ecc_size) {
> +	case 512:
> +		start = 1;
> +		if (!ecc_strength_ds)
> +			ecc_strength_ds = 4;
> +		break;
> +	case 1024:
> +		start = 4;
> +		if (!ecc_strength_ds)
> +			ecc_strength_ds = 32;
> +		break;
> +	default:
> +		return -EINVAL;
> +	}
> +
> +	/* BCH ECC algorithm Settings for number of bits per 512B/1024B */
> +	bch_algo = round_up(start + 1, 4);
> +	for (val = start; val < bch_algo; val++) {
> +		if (ecc_strength_ds == ecc_strength[val])
> +			break;
> +	}
> +	if (val == bch_algo)
> +		return -EINVAL;
> +
> +	if (ecc_strength_ds == 8)
> +		ecc_bytes = 14;
> +	else
> +		ecc_bytes = DIV_ROUND_UP(ecc_strength_ds * fls(8 * ecc_size), 8);
> +
> +	ecc_steps = writesize / ecc_size;
> +	ecc_total = ecc_steps * ecc_bytes;
> +	if ((ecc_total + 8) > mtd->oobsize)
> +		return -ERANGE;
> +
> +	chip->ecc.total = ecc_total;
> +	pagesize = fls(writesize >> 11);
> +	if (pagesize > HSNAND_PARA0_PAGE_V8192)
> +		return -ERANGE;
> +
> +	pg_per_blk = fls((blocksize / writesize) >> 6) << 4;

If << 4 is here to mean / 8, then I don't want a shift operation
because it is highly unreadable and compilers know how to optimize
this.

> +	if (pg_per_blk > HSNAND_PARA0_PIB_V256)
> +		return -ERANGE;
> +
> +	ebu_host->nd_para0 = pagesize | pg_per_blk | HSNAND_PARA0_BYP_EN_NP |
> +			     HSNAND_PARA0_BYP_DEC_NP | HSNAND_PARA0_ADEP_EN |
> +			     HSNAND_PARA0_TYPE_ONFI | (val << 29);
> +
> +	mtd_set_ooblayout(mtd, &ebu_nand_ooblayout_ops);
> +	chip->ecc.read_page = ebu_nand_read_page_hwecc;
> +	chip->ecc.write_page = ebu_nand_write_page_hwecc;
> +
> +	return 0;
> +}
> +
> +static int ebu_nand_exec_op(struct nand_chip *chip,
> +			    const struct nand_operation *op, bool check_only)
> +{
> +	struct ebu_nand_controller *ctrl = nand_to_ebu(chip);
> +	const struct nand_op_instr *instr = NULL;
> +	unsigned int op_id;
> +	int i, time_out, ret = 0;
> +	u32 stat;
> +
> +	if (check_only)
> +		ebu_select_chip(chip);

What is the point of selecting the chip if check_only is true?

> +
> +	for (op_id = 0; op_id < op->ninstrs; op_id++) {
> +		instr = &op->instrs[op_id];
> +
> +		switch (instr->type) {
> +		case NAND_OP_CMD_INSTR:
> +			ebu_nand_writeb(chip, HSNAND_CLE_OFFS | HSNAND_CS_OFFS,
> +					instr->ctx.cmd.opcode);
> +			break;
> +
> +		case NAND_OP_ADDR_INSTR:
> +			for (i = 0; i < instr->ctx.addr.naddrs; i++)
> +				ebu_nand_writeb(chip,
> +						HSNAND_ALE_OFFS | HSNAND_CS_OFFS,
> +						instr->ctx.addr.addrs[i]);
> +			break;
> +
> +		case NAND_OP_DATA_IN_INSTR:
> +			ebu_read_buf(chip, instr->ctx.data.buf.in,
> +				     instr->ctx.data.len);
> +			break;
> +
> +		case NAND_OP_DATA_OUT_INSTR:
> +			ebu_write_buf(chip, instr->ctx.data.buf.out,
> +				      instr->ctx.data.len);
> +			break;
> +
> +		case NAND_OP_WAITRDY_INSTR:
> +			time_out = instr->ctx.waitrdy.timeout_ms * 1000;
> +			ret = readl_poll_timeout(ctrl->ebu + EBU_WAIT,
> +						 stat, stat & EBU_WAIT_RDBY,
> +						 20, time_out);
> +			break;
> +		}
> +	}
> +
> +	return ret;
> +}


Thanks,
Miquèl