linux-kernel - Re: [PATCH 2/5] drivers: mtd: nand: Add qpic

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Message-ID: <4cb0144c-303b-4b91-bf88-0a7d7412afe1@linaro.org>
Date: Thu, 15 Feb 2024 18:55:11 +0100
From: Konrad Dybcio <konrad.dybcio@...aro.org>
To: Md Sadre Alam <quic_mdalam@...cinc.com>, andersson@...nel.org,
 broonie@...nel.org, robh@...nel.org, krzysztof.kozlowski+dt@...aro.org,
 conor+dt@...nel.org, miquel.raynal@...tlin.com, richard@....at,
 vigneshr@...com, manivannan.sadhasivam@...aro.org,
 linux-arm-msm@...r.kernel.org, linux-spi@...r.kernel.org,
 devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-mtd@...ts.infradead.org
Cc: quic_srichara@...cinc.com, quic_varada@...cinc.com
Subject: Re: [PATCH 2/5] drivers: mtd: nand: Add qpic_common API file

On 15.02.2024 14:48, Md Sadre Alam wrote:
> Add qpic_common.c file which hold all the common
> qpic APIs which will be used by both qpic raw nand
> driver and qpic spi nand driver.
> 
> Co-developed-by: Sricharan Ramabadhran <quic_srichara@...cinc.com>
> Signed-off-by: Sricharan Ramabadhran <quic_srichara@...cinc.com>
> Co-developed-by: Varadarajan Narayanan <quic_varada@...cinc.com>
> Signed-off-by: Varadarajan Narayanan <quic_varada@...cinc.com>
> Signed-off-by: Md Sadre Alam <quic_mdalam@...cinc.com>
> ---

IIUC this is mostly moving code around?

I do however have some suggestions..

>  drivers/mtd/nand/Makefile            |    1 +
>  drivers/mtd/nand/qpic_common.c       |  786 +++++++++++++++++
>  drivers/mtd/nand/raw/qcom_nandc.c    | 1226 +-------------------------
>  include/linux/mtd/nand-qpic-common.h |  488 ++++++++++
>  4 files changed, 1291 insertions(+), 1210 deletions(-)
>  create mode 100644 drivers/mtd/nand/qpic_common.c
>  create mode 100644 include/linux/mtd/nand-qpic-common.h
> 
> diff --git a/drivers/mtd/nand/Makefile b/drivers/mtd/nand/Makefile
> index 19e1291ac4d5..131707a41293 100644
> --- a/drivers/mtd/nand/Makefile
> +++ b/drivers/mtd/nand/Makefile
> @@ -12,3 +12,4 @@ nandcore-$(CONFIG_MTD_NAND_ECC) += ecc.o
>  nandcore-$(CONFIG_MTD_NAND_ECC_SW_HAMMING) += ecc-sw-hamming.o
>  nandcore-$(CONFIG_MTD_NAND_ECC_SW_BCH) += ecc-sw-bch.o
>  nandcore-$(CONFIG_MTD_NAND_ECC_MXIC) += ecc-mxic.o
> +obj-y += qpic_common.o
> diff --git a/drivers/mtd/nand/qpic_common.c b/drivers/mtd/nand/qpic_common.c
> new file mode 100644
> index 000000000000..4d74ba888028
> --- /dev/null
> +++ b/drivers/mtd/nand/qpic_common.c
> @@ -0,0 +1,786 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * QPIC Controller common API file.
> + * Copyright (C) 2023  Qualcomm Inc.
> + * Authors:	Md sadre Alam           <quic_mdalam@...cinc.com>
> + *		Sricharan R             <quic_srichara@...cinc.com>
> + *		Varadarajan Narayanan	<quic_varada@...cinc.com>
> + *
> + */
> +
> +#include <linux/mtd/nand-qpic-common.h>
> +
> +struct qcom_nand_controller *
> +get_qcom_nand_controller(struct nand_chip *chip)
> +{
> +	return container_of(chip->controller, struct qcom_nand_controller,
> +			    controller);
> +}
> +EXPORT_SYMBOL(get_qcom_nand_controller);

#define to_qcom_nand_controller()?

> +
> +/*
> + * Helper to prepare DMA descriptors for configuring registers
> + * before reading a NAND page.
> + */

Can you convert these to kerneldoc instead?

> +void config_nand_page_read(struct nand_chip *chip)
> +{
> +	struct qcom_nand_controller *nandc = get_qcom_nand_controller(chip);
> +
> +	write_reg_dma(nandc, NAND_ADDR0, 2, 0);
> +	write_reg_dma(nandc, NAND_DEV0_CFG0, 3, 0);
> +	if (!nandc->props->qpic_v2)

This is not going to scale going forward.. please include a version
enum instead.

[...]

> +
> +int prep_adm_dma_desc(struct qcom_nand_controller *nandc, bool read,
> +		      int reg_off, const void *vaddr, int size,
> +			     bool flow_control)
> +{
> +	struct desc_info *desc;
> +	struct dma_async_tx_descriptor *dma_desc;
> +	struct scatterlist *sgl;
> +	struct dma_slave_config slave_conf;
> +	struct qcom_adm_peripheral_config periph_conf = {};
> +	enum dma_transfer_direction dir_eng;
> +	int ret;

Revertse-christmas-tree, please

> +
> +	desc = kzalloc(sizeof(*desc), GFP_KERNEL);
> +	if (!desc)
> +		return -ENOMEM;
> +
> +	sgl = &desc->adm_sgl;
> +
> +	sg_init_one(sgl, vaddr, size);
> +
> +	if (read) {
> +		dir_eng = DMA_DEV_TO_MEM;
> +		desc->dir = DMA_FROM_DEVICE;
> +	} else {
> +		dir_eng = DMA_MEM_TO_DEV;
> +		desc->dir = DMA_TO_DEVICE;
> +	}
> +
> +	ret = dma_map_sg(nandc->dev, sgl, 1, desc->dir);
> +	if (ret == 0) {

if (!ret)

> +		ret = -ENOMEM;
> +		goto err;
> +	}
> +
> +	memset(&slave_conf, 0x00, sizeof(slave_conf));

Just zero-initialize it (= { 0 }) at declaration time

Konrad