Re: [PATCH v7 3/9] spi: Add a driver for the Freescale/NXP QuadSPI controller

From: Schrempf Frieder
Date: Fri Dec 07 2018 - 04:27:27 EST

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On 07.12.18 06:46, Yogesh Narayan Gaur wrote:
> Hi Frieder,
>
>> -----Original Message-----
>> From: Schrempf Frieder [mailto:frieder.schrempf@xxxxxxxxxx]
>> Sent: Tuesday, December 4, 2018 7:45 PM
>> To: linux-mtd@xxxxxxxxxxxxxxxxxxx; boris.brezillon@xxxxxxxxxxx; linux-
>> spi@xxxxxxxxxxxxxxx; Marek Vasut <marek.vasut@xxxxxxxxx>; Mark Brown
>> <broonie@xxxxxxxxxx>; Han Xu <han.xu@xxxxxxx>
>> Cc: dwmw2@xxxxxxxxxxxxx; computersforpeace@xxxxxxxxx; richard@xxxxxx;
>> miquel.raynal@xxxxxxxxxxx; David Wolfe <david.wolfe@xxxxxxx>; Fabio
>> Estevam <fabio.estevam@xxxxxxx>; Prabhakar Kushwaha
>> <prabhakar.kushwaha@xxxxxxx>; Yogesh Narayan Gaur
>> <yogeshnarayan.gaur@xxxxxxx>; shawnguo@xxxxxxxxxx; Schrempf Frieder
>> <frieder.schrempf@xxxxxxxxxx>; linux-kernel@xxxxxxxxxxxxxxx
>> Subject: [PATCH v7 3/9] spi: Add a driver for the Freescale/NXP QuadSPI
>> controller
>>
>> From: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
>>
>> This driver is derived from the SPI NOR driver at mtd/spi-nor/fsl-quadspi.c. It
>> uses the new SPI memory interface of the SPI framework to issue flash memory
>> operations to up to four connected flash chips (2 buses with 2 CS each).
>>
>> The controller does not support generic SPI messages.
>>
>> This patch also disables the build of the "old" driver and reuses its Kconfig option
>> CONFIG_SPI_FSL_QUADSPI to replace it.
>>
>> Signed-off-by: Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
>> ---
>> drivers/mtd/spi-nor/Kconfig | 9 -
>> drivers/mtd/spi-nor/Makefile | 1 -
>> drivers/spi/Kconfig | 11 +
>> drivers/spi/Makefile | 1 +
>> drivers/spi/spi-fsl-qspi.c | 966 ++++++++++++++++++++++++++++++++++++++
>> 5 files changed, 978 insertions(+), 10 deletions(-)
>>
>> diff --git a/drivers/mtd/spi-nor/Kconfig b/drivers/mtd/spi-nor/Kconfig index
>> 6cc9c92..d1ca307 100644
>> --- a/drivers/mtd/spi-nor/Kconfig
>> +++ b/drivers/mtd/spi-nor/Kconfig
>> @@ -59,15 +59,6 @@ config SPI_CADENCE_QUADSPI
>> device with a Cadence QSPI controller and want to access the
>> Flash as an MTD device.
>>
>> -config SPI_FSL_QUADSPI
>> - tristate "Freescale Quad SPI controller"
>> - depends on ARCH_MXC || SOC_LS1021A || ARCH_LAYERSCAPE ||
>> COMPILE_TEST
>> - depends on HAS_IOMEM
>> - help
>> - This enables support for the Quad SPI controller in master mode.
>> - This controller does not support generic SPI. It only supports
>> - SPI NOR.
>> -
>> config SPI_HISI_SFC
>> tristate "Hisilicon SPI-NOR Flash Controller(SFC)"
>> depends on ARCH_HISI || COMPILE_TEST
>> diff --git a/drivers/mtd/spi-nor/Makefile b/drivers/mtd/spi-nor/Makefile index
>> f4c61d2..3f160c2e3 100644
>> --- a/drivers/mtd/spi-nor/Makefile
>> +++ b/drivers/mtd/spi-nor/Makefile
>> @@ -3,7 +3,6 @@ obj-$(CONFIG_MTD_SPI_NOR) += spi-nor.o
>> obj-$(CONFIG_SPI_ASPEED_SMC) += aspeed-smc.o
>> obj-$(CONFIG_SPI_ATMEL_QUADSPI) += atmel-quadspi.o
>> obj-$(CONFIG_SPI_CADENCE_QUADSPI) += cadence-quadspi.o
>> -obj-$(CONFIG_SPI_FSL_QUADSPI) += fsl-quadspi.o
>> obj-$(CONFIG_SPI_HISI_SFC) += hisi-sfc.o
>> obj-$(CONFIG_MTD_MT81xx_NOR) += mtk-quadspi.o
>> obj-$(CONFIG_SPI_NXP_SPIFI) += nxp-spifi.o
>> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig index 7d3a5c9..8c84186
>> 100644
>> --- a/drivers/spi/Kconfig
>> +++ b/drivers/spi/Kconfig
>> @@ -259,6 +259,17 @@ config SPI_FSL_LPSPI
>> help
>> This enables Freescale i.MX LPSPI controllers in master mode.
>>
>> +config SPI_FSL_QUADSPI
>> + tristate "Freescale QSPI controller"
>> + depends on ARCH_MXC || SOC_LS1021A || ARCH_LAYERSCAPE ||
>> COMPILE_TEST
>> + depends on HAS_IOMEM
>> + help
>> + This enables support for the Quad SPI controller in master mode.
>> + Up to four flash chips can be connected on two buses with two
>> + chipselects each.
>> + This controller does not support generic SPI messages. It only
>> + supports the high-level SPI memory interface.
>> +
>> config SPI_GPIO
>> tristate "GPIO-based bitbanging SPI Master"
>> depends on GPIOLIB || COMPILE_TEST
>> diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile index 3575205..5377e61
>> 100644
>> --- a/drivers/spi/Makefile
>> +++ b/drivers/spi/Makefile
>> @@ -44,6 +44,7 @@ obj-$(CONFIG_SPI_FSL_DSPI) += spi-fsl-
>> dspi.o
>> obj-$(CONFIG_SPI_FSL_LIB) += spi-fsl-lib.o
>> obj-$(CONFIG_SPI_FSL_ESPI) += spi-fsl-espi.o
>> obj-$(CONFIG_SPI_FSL_LPSPI) += spi-fsl-lpspi.o
>> +obj-$(CONFIG_SPI_FSL_QUADSPI) += spi-fsl-qspi.o
>> obj-$(CONFIG_SPI_FSL_SPI) += spi-fsl-spi.o
>> obj-$(CONFIG_SPI_GPIO) += spi-gpio.o
>> obj-$(CONFIG_SPI_IMG_SPFI) += spi-img-spfi.o
>> diff --git a/drivers/spi/spi-fsl-qspi.c b/drivers/spi/spi-fsl-qspi.c new file mode
>> 100644 index 0000000..f0a3400
>> --- /dev/null
>> +++ b/drivers/spi/spi-fsl-qspi.c
>> @@ -0,0 +1,966 @@
>> +// SPDX-License-Identifier: GPL-2.0+
>> +
>> +/*
>> + * Freescale QuadSPI driver.
>> + *
>> + * Copyright (C) 2013 Freescale Semiconductor, Inc.
>> + * Copyright (C) 2018 Bootlin
>> + * Copyright (C) 2018 exceet electronics GmbH
>> + * Copyright (C) 2018 Kontron Electronics GmbH
>> + *
>> + * Transition to SPI MEM interface:
>> + * Authors:
>> + * Boris Brezillion <boris.brezillon@xxxxxxxxxxx>
>> + * Frieder Schrempf <frieder.schrempf@xxxxxxxxxx>
>> + * Yogesh Gaur <yogeshnarayan.gaur@xxxxxxx>
>> + * Suresh Gupta <suresh.gupta@xxxxxxx>
>> + *
>> + * Based on the original fsl-quadspi.c spi-nor driver:
>> + * Author: Freescale Semiconductor, Inc.
>> + *
>> + */
>> +
>> +#include <linux/bitops.h>
>> +#include <linux/clk.h>
>> +#include <linux/completion.h>
>> +#include <linux/delay.h>
>> +#include <linux/err.h>
>> +#include <linux/errno.h>
>> +#include <linux/interrupt.h>
>> +#include <linux/io.h>
>> +#include <linux/iopoll.h>
>> +#include <linux/jiffies.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/mutex.h>
>> +#include <linux/of.h>
>> +#include <linux/of_device.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/pm_qos.h>
>> +#include <linux/sizes.h>
>> +
>> +#include <linux/spi/spi.h>
>> +#include <linux/spi/spi-mem.h>
>> +
>> +/*
>> + * The driver only uses one single LUT entry, that is updated on
>> + * each call of exec_op(). Index 0 is preset at boot with a basic
>> + * read operation, so let's use the last entry (15).
>> + */
>> +#define SEQID_LUT 15
>> +
>> +/* Registers used by the driver */
>> +#define QUADSPI_MCR 0x00
>> +#define QUADSPI_MCR_RESERVED_MASK GENMASK(19, 16)
>> +#define QUADSPI_MCR_MDIS_MASK BIT(14)
>> +#define QUADSPI_MCR_CLR_TXF_MASK BIT(11)
>> +#define QUADSPI_MCR_CLR_RXF_MASK BIT(10)
>> +#define QUADSPI_MCR_DDR_EN_MASK BIT(7)
>> +#define QUADSPI_MCR_END_CFG_MASK GENMASK(3, 2)
>> +#define QUADSPI_MCR_SWRSTHD_MASK BIT(1)
>> +#define QUADSPI_MCR_SWRSTSD_MASK BIT(0)
>> +
>> +#define QUADSPI_IPCR 0x08
>> +#define QUADSPI_IPCR_SEQID(x) ((x) << 24)
>> +
>> +#define QUADSPI_BUF3CR 0x1c
>> +#define QUADSPI_BUF3CR_ALLMST_MASK BIT(31)
>> +#define QUADSPI_BUF3CR_ADATSZ(x) ((x) << 8)
>> +#define QUADSPI_BUF3CR_ADATSZ_MASK GENMASK(15, 8)
>> +
>> +#define QUADSPI_BFGENCR 0x20
>> +#define QUADSPI_BFGENCR_SEQID(x) ((x) << 12)
>> +
>> +#define QUADSPI_BUF0IND 0x30
>> +#define QUADSPI_BUF1IND 0x34
>> +#define QUADSPI_BUF2IND 0x38
>> +#define QUADSPI_SFAR 0x100
>> +
>> +#define QUADSPI_SMPR 0x108
>> +#define QUADSPI_SMPR_DDRSMP_MASK GENMASK(18, 16)
>> +#define QUADSPI_SMPR_FSDLY_MASK BIT(6)
>> +#define QUADSPI_SMPR_FSPHS_MASK BIT(5)
>> +#define QUADSPI_SMPR_HSENA_MASK BIT(0)
>> +
>> +#define QUADSPI_RBCT 0x110
>> +#define QUADSPI_RBCT_WMRK_MASK GENMASK(4, 0)
>> +#define QUADSPI_RBCT_RXBRD_USEIPS BIT(8)
>> +
>> +#define QUADSPI_TBDR 0x154
>> +
>> +#define QUADSPI_SR 0x15c
>> +#define QUADSPI_SR_IP_ACC_MASK BIT(1)
>> +#define QUADSPI_SR_AHB_ACC_MASK BIT(2)
>> +
>> +#define QUADSPI_FR 0x160
>> +#define QUADSPI_FR_TFF_MASK BIT(0)
>> +
>> +#define QUADSPI_SPTRCLR 0x16c
>> +#define QUADSPI_SPTRCLR_IPPTRC BIT(8)
>> +#define QUADSPI_SPTRCLR_BFPTRC BIT(0)
>> +
>> +#define QUADSPI_SFA1AD 0x180
>> +#define QUADSPI_SFA2AD 0x184
>> +#define QUADSPI_SFB1AD 0x188
>> +#define QUADSPI_SFB2AD 0x18c
>> +#define QUADSPI_RBDR(x) (0x200 + ((x) * 4))
>> +
>> +#define QUADSPI_LUTKEY 0x300
>> +#define QUADSPI_LUTKEY_VALUE 0x5AF05AF0
>> +
>> +#define QUADSPI_LCKCR 0x304
>> +#define QUADSPI_LCKER_LOCK BIT(0)
>> +#define QUADSPI_LCKER_UNLOCK BIT(1)
>> +
>> +#define QUADSPI_RSER 0x164
>> +#define QUADSPI_RSER_TFIE BIT(0)
>> +
>> +#define QUADSPI_LUT_BASE 0x310
>> +#define QUADSPI_LUT_OFFSET (SEQID_LUT * 4 * 4)
>> +#define QUADSPI_LUT_REG(idx) \
>> + (QUADSPI_LUT_BASE + QUADSPI_LUT_OFFSET + (idx) * 4)
>> +
>> +/* Instruction set for the LUT register */
>> +#define LUT_STOP 0
>> +#define LUT_CMD 1
>> +#define LUT_ADDR 2
>> +#define LUT_DUMMY 3
>> +#define LUT_MODE 4
>> +#define LUT_MODE2 5
>> +#define LUT_MODE4 6
>> +#define LUT_FSL_READ 7
>> +#define LUT_FSL_WRITE 8
>> +#define LUT_JMP_ON_CS 9
>> +#define LUT_ADDR_DDR 10
>> +#define LUT_MODE_DDR 11
>> +#define LUT_MODE2_DDR 12
>> +#define LUT_MODE4_DDR 13
>> +#define LUT_FSL_READ_DDR 14
>> +#define LUT_FSL_WRITE_DDR 15
>> +#define LUT_DATA_LEARN 16
>> +
>> +/*
>> + * The PAD definitions for LUT register.
>> + *
>> + * The pad stands for the number of IO lines [0:3].
>> + * For example, the quad read needs four IO lines,
>> + * so you should use LUT_PAD(4).
>> + */
>> +#define LUT_PAD(x) (fls(x) - 1)
>> +
>> +/*
>> + * Macro for constructing the LUT entries with the following
>> + * register layout:
>> + *
>> + * ---------------------------------------------------
>> + * | INSTR1 | PAD1 | OPRND1 | INSTR0 | PAD0 | OPRND0 |
>> + * ---------------------------------------------------
>> + */
>> +#define LUT_DEF(idx, ins, pad, opr) \
>> + ((((ins) << 10) | ((pad) << 8) | (opr)) << (((idx) % 2) * 16))
>> +
>> +/* Controller needs driver to swap endianness */
>> +#define QUADSPI_QUIRK_SWAP_ENDIAN BIT(0)
>> +
>> +/* Controller needs 4x internal clock */
>> +#define QUADSPI_QUIRK_4X_INT_CLK BIT(1)
>> +
>> +/*
>> + * TKT253890, the controller needs the driver to fill the txfifo with
>> + * 16 bytes at least to trigger a data transfer, even though the extra
>> + * data won't be transferred.
>> + */
>> +#define QUADSPI_QUIRK_TKT253890 BIT(2)
>> +
>> +/* TKT245618, the controller cannot wake up from wait mode */
>> +#define QUADSPI_QUIRK_TKT245618 BIT(3)
>> +
>> +/*
>> + * Controller adds QSPI_AMBA_BASE (base address of the mapped memory)
>> + * internally. No need to add it when setting SFXXAD and SFAR registers
>> +*/
>> +#define QUADSPI_QUIRK_BASE_INTERNAL BIT(4)
>> +
>> +struct fsl_qspi_devtype_data {
>> + unsigned int rxfifo;
>> + unsigned int txfifo;
>> + unsigned int ahb_buf_size;
>> + unsigned int quirks;
>> + bool little_endian;
>> +};
>> +
>> +static const struct fsl_qspi_devtype_data vybrid_data = {
>> + .rxfifo = SZ_128,
>> + .txfifo = SZ_64,
>> + .ahb_buf_size = SZ_1K,
>> + .quirks = QUADSPI_QUIRK_SWAP_ENDIAN,
>> + .little_endian = true,
>> +};
>> +
>> +static const struct fsl_qspi_devtype_data imx6sx_data = {
>> + .rxfifo = SZ_128,
>> + .txfifo = SZ_512,
>> + .ahb_buf_size = SZ_1K,
>> + .quirks = QUADSPI_QUIRK_4X_INT_CLK | QUADSPI_QUIRK_TKT245618,
>> + .little_endian = true,
>> +};
>> +
>> +static const struct fsl_qspi_devtype_data imx7d_data = {
>> + .rxfifo = SZ_512,
>> + .txfifo = SZ_512,
>> + .ahb_buf_size = SZ_1K,
>> + .quirks = QUADSPI_QUIRK_TKT253890 | QUADSPI_QUIRK_4X_INT_CLK,
>> + .little_endian = true,
>> +};
>> +
>> +static const struct fsl_qspi_devtype_data imx6ul_data = {
>> + .rxfifo = SZ_128,
>> + .txfifo = SZ_512,
>> + .ahb_buf_size = SZ_1K,
>> + .quirks = QUADSPI_QUIRK_TKT253890 | QUADSPI_QUIRK_4X_INT_CLK,
>> + .little_endian = true,
>> +};
>> +
>> +static const struct fsl_qspi_devtype_data ls1021a_data = {
>> + .rxfifo = SZ_128,
>> + .txfifo = SZ_64,
>> + .ahb_buf_size = SZ_1K,
>> + .quirks = 0,
>> + .little_endian = false,
>> +};
>> +
>> +static const struct fsl_qspi_devtype_data ls2080a_data = {
>> + .rxfifo = SZ_128,
>> + .txfifo = SZ_64,
>> + .ahb_buf_size = SZ_1K,
>> + .quirks = QUADSPI_QUIRK_TKT253890 |
>> QUADSPI_QUIRK_BASE_INTERNAL,
>> + .little_endian = true,
>> +};
>> +
>> +struct fsl_qspi {
>> + void __iomem *iobase;
>> + void __iomem *ahb_addr;
>> + u32 memmap_phy;
>> + struct clk *clk, *clk_en;
>> + struct device *dev;
>> + struct completion c;
>> + const struct fsl_qspi_devtype_data *devtype_data;
>> + struct mutex lock;
>> + struct pm_qos_request pm_qos_req;
>> + int selected;
>> +};
>> +
>> +static inline int needs_swap_endian(struct fsl_qspi *q) {
>> + return q->devtype_data->quirks & QUADSPI_QUIRK_SWAP_ENDIAN; }
>> +
>> +static inline int needs_4x_clock(struct fsl_qspi *q) {
>> + return q->devtype_data->quirks & QUADSPI_QUIRK_4X_INT_CLK; }
>> +
>> +static inline int needs_fill_txfifo(struct fsl_qspi *q) {
>> + return q->devtype_data->quirks & QUADSPI_QUIRK_TKT253890; }
>> +
>> +static inline int needs_wakeup_wait_mode(struct fsl_qspi *q) {
>> + return q->devtype_data->quirks & QUADSPI_QUIRK_TKT245618; }
>> +
>> +static inline int needs_amba_base_offset(struct fsl_qspi *q) {
>> + return !(q->devtype_data->quirks &
>> QUADSPI_QUIRK_BASE_INTERNAL); }
>> +
>> +/*
>> + * An IC bug makes it necessary to rearrange the 32-bit data.
>> + * Later chips, such as IMX6SLX, have fixed this bug.
>> + */
>> +static inline u32 fsl_qspi_endian_xchg(struct fsl_qspi *q, u32 a) {
>> + return needs_swap_endian(q) ? __swab32(a) : a; }
>> +
>> +/*
>> + * R/W functions for big- or little-endian registers:
>> + * The QSPI controller's endianness is independent of
>> + * the CPU core's endianness. So far, although the CPU
>> + * core is little-endian the QSPI controller can use
>> + * big-endian or little-endian.
>> + */
>> +static void qspi_writel(struct fsl_qspi *q, u32 val, void __iomem
>> +*addr) {
>> + if (q->devtype_data->little_endian)
>> + iowrite32(val, addr);
>> + else
>> + iowrite32be(val, addr);
>> +}
>> +
>> +static u32 qspi_readl(struct fsl_qspi *q, void __iomem *addr) {
>> + if (q->devtype_data->little_endian)
>> + return ioread32(addr);
>> +
>> + return ioread32be(addr);
>> +}
>> +
>> +static irqreturn_t fsl_qspi_irq_handler(int irq, void *dev_id) {
>> + struct fsl_qspi *q = dev_id;
>> + u32 reg;
>> +
>> + /* clear interrupt */
>> + reg = qspi_readl(q, q->iobase + QUADSPI_FR);
>> + qspi_writel(q, reg, q->iobase + QUADSPI_FR);
>> +
>> + if (reg & QUADSPI_FR_TFF_MASK)
>> + complete(&q->c);
>> +
>> + dev_dbg(q->dev, "QUADSPI_FR : 0x%.8x:0x%.8x\n", 0, reg);
>> + return IRQ_HANDLED;
>> +}
>> +
>> +static int fsl_qspi_check_buswidth(struct fsl_qspi *q, u8 width) {
>> + switch (width) {
>> + case 1:
>> + case 2:
>> + case 4:
>> + return 0;
>> + }
>> +
>> + return -ENOTSUPP;
>> +}
>> +
>> +static bool fsl_qspi_supports_op(struct spi_mem *mem,
>> + const struct spi_mem_op *op)
>> +{
>> + struct fsl_qspi *q = spi_controller_get_devdata(mem->spi->master);
>> + int ret;
>> +
>> + ret = fsl_qspi_check_buswidth(q, op->cmd.buswidth);
>> +
>> + if (op->addr.nbytes)
>> + ret |= fsl_qspi_check_buswidth(q, op->addr.buswidth);
>> +
>> + if (op->dummy.nbytes)
>> + ret |= fsl_qspi_check_buswidth(q, op->dummy.buswidth);
>> +
>> + if (op->data.nbytes)
>> + ret |= fsl_qspi_check_buswidth(q, op->data.buswidth);
>> +
>> + if (ret)
>> + return false;
>> +
>> + /*
>> + * The number of instructions needed for the op, needs
>> + * to fit into a single LUT entry.
>> + */
>> + if (op->addr.nbytes +
>> + (op->dummy.nbytes ? 1:0) +
>> + (op->data.nbytes ? 1:0) > 6)
>> + return false;
>> +
>> + /* Max 64 dummy clock cycles supported */
>> + if (op->dummy.nbytes &&
>> + (op->dummy.nbytes * 8 / op->dummy.buswidth > 64))
>> + return false;
>> +
>> + /* Max data length, check controller limits and alignment */
>> + if (op->data.dir == SPI_MEM_DATA_IN &&
>> + (op->data.nbytes > q->devtype_data->ahb_buf_size ||
>> + (op->data.nbytes > q->devtype_data->rxfifo - 4 &&
>> + !IS_ALIGNED(op->data.nbytes, 8))))
>> + return false;
>> +
>> + if (op->data.dir == SPI_MEM_DATA_OUT &&
>> + op->data.nbytes > q->devtype_data->txfifo)
>> + return false;
>> +
>> + return true;
>> +}
>> +
>> +static void fsl_qspi_prepare_lut(struct fsl_qspi *q,
>> + const struct spi_mem_op *op)
>> +{
>> + void __iomem *base = q->iobase;
>> + u32 lutval[4] = {};
>> + int lutidx = 1, i;
>> +
>> + lutval[0] |= LUT_DEF(0, LUT_CMD, LUT_PAD(op->cmd.buswidth),
>> + op->cmd.opcode);
>> +
>> + /*
>> + * For some unknown reason, using LUT_ADDR doesn't work in some
>> + * cases (at least with only one byte long addresses), so
>> + * let's use LUT_MODE to write the address bytes one by one
>> + */
>> + for (i = 0; i < op->addr.nbytes; i++) {
>> + u8 addrbyte = op->addr.val >> (8 * (op->addr.nbytes - i - 1));
>> +
>> + lutval[lutidx / 2] |= LUT_DEF(lutidx, LUT_MODE,
>> + LUT_PAD(op->addr.buswidth),
>> + addrbyte);
>> + lutidx++;
>> + }
>> +
>> + if (op->dummy.nbytes) {
>> + lutval[lutidx / 2] |= LUT_DEF(lutidx, LUT_DUMMY,
>> + LUT_PAD(op->dummy.buswidth),
>> + op->dummy.nbytes * 8 /
>> + op->dummy.buswidth);
>> + lutidx++;
>> + }
>> +
>> + if (op->data.nbytes) {
>> + lutval[lutidx / 2] |= LUT_DEF(lutidx,
>> + op->data.dir ==
>> SPI_MEM_DATA_IN ?
>> + LUT_FSL_READ : LUT_FSL_WRITE,
>> + LUT_PAD(op->data.buswidth),
>> + 0);
>> + lutidx++;
>> + }
>> +
>> + lutval[lutidx / 2] |= LUT_DEF(lutidx, LUT_STOP, 0, 0);
>> +
>> + /* unlock LUT */
>> + qspi_writel(q, QUADSPI_LUTKEY_VALUE, q->iobase + QUADSPI_LUTKEY);
>> + qspi_writel(q, QUADSPI_LCKER_UNLOCK, q->iobase + QUADSPI_LCKCR);
>> +
>> + /* fill LUT */
>> + for (i = 0; i < ARRAY_SIZE(lutval); i++)
>> + qspi_writel(q, lutval[i], base + QUADSPI_LUT_REG(i));
>> +
>> + /* lock LUT */
>> + qspi_writel(q, QUADSPI_LUTKEY_VALUE, q->iobase + QUADSPI_LUTKEY);
>> + qspi_writel(q, QUADSPI_LCKER_LOCK, q->iobase + QUADSPI_LCKCR); }
>> +
>> +static int fsl_qspi_clk_prep_enable(struct fsl_qspi *q) {
>> + int ret;
>> +
>> + ret = clk_prepare_enable(q->clk_en);
>> + if (ret)
>> + return ret;
>> +
>> + ret = clk_prepare_enable(q->clk);
>> + if (ret) {
>> + clk_disable_unprepare(q->clk_en);
>> + return ret;
>> + }
>> +
>> + if (needs_wakeup_wait_mode(q))
>> + pm_qos_add_request(&q->pm_qos_req,
>> PM_QOS_CPU_DMA_LATENCY, 0);
>> +
>> + return 0;
>> +}
>> +
>> +static void fsl_qspi_clk_disable_unprep(struct fsl_qspi *q) {
>> + if (needs_wakeup_wait_mode(q))
>> + pm_qos_remove_request(&q->pm_qos_req);
>> +
>> + clk_disable_unprepare(q->clk);
>> + clk_disable_unprepare(q->clk_en);
>> +}
>> +
>> +/*
>> + * If we have changed the content of the flash by writing or erasing,
>> +or if we
>> + * read from flash with a different offset into the page buffer, we
>> +need to
>> + * invalidate the AHB buffer. If we do not do so, we may read out the
>> +wrong
>> + * data. The spec tells us reset the AHB domain and Serial Flash domain
>> +at
>> + * the same time.
>> + */
>> +static void fsl_qspi_invalidate(struct fsl_qspi *q) {
>> + u32 reg;
>> +
>> + reg = qspi_readl(q, q->iobase + QUADSPI_MCR);
>> + reg |= QUADSPI_MCR_SWRSTHD_MASK |
>> QUADSPI_MCR_SWRSTSD_MASK;
>> + qspi_writel(q, reg, q->iobase + QUADSPI_MCR);
>> +
>> + /*
>> + * The minimum delay : 1 AHB + 2 SFCK clocks.
>> + * Delay 1 us is enough.
>> + */
>> + udelay(1);
>> +
>> + reg &= ~(QUADSPI_MCR_SWRSTHD_MASK |
>> QUADSPI_MCR_SWRSTSD_MASK);
>> + qspi_writel(q, reg, q->iobase + QUADSPI_MCR); }
>> +
>> +static void fsl_qspi_select_mem(struct fsl_qspi *q, struct spi_device
>> +*spi) {
>> + unsigned long rate = spi->max_speed_hz;
>> + int ret;
>> +
>> + if (q->selected == spi->chip_select)
>> + return;
>> +
>> + if (needs_4x_clock(q))
>> + rate *= 4;
>> +
>> + fsl_qspi_clk_disable_unprep(q);
>> +
>> + ret = clk_set_rate(q->clk, rate);
>> + if (ret)
>> + return;
>> +
>> + ret = fsl_qspi_clk_prep_enable(q);
>> + if (ret)
>> + return;
>> +
>> + q->selected = spi->chip_select;
>> +
>> + fsl_qspi_invalidate(q);
>> +}
>> +
>> +static void fsl_qspi_read_ahb(struct fsl_qspi *q, const struct
>> +spi_mem_op *op) {
>> + memcpy_fromio(op->data.buf.in,
>> + q->ahb_addr + q->selected * q->devtype_data-
>>> ahb_buf_size,
>> + op->data.nbytes);
>> +}
>> +
>> +static void fsl_qspi_fill_txfifo(struct fsl_qspi *q,
>> + const struct spi_mem_op *op)
>> +{
>> + void __iomem *base = q->iobase;
>> + int i;
>> + u32 val;
>> +
>> + for (i = 0; i < ALIGN_DOWN(op->data.nbytes, 4); i += 4) {
>> + memcpy(&val, op->data.buf.out + i, 4);
>> + val = fsl_qspi_endian_xchg(q, val);
>> + qspi_writel(q, val, base + QUADSPI_TBDR);
>> + }
>> +
>> + if (i < op->data.nbytes) {
>> + memcpy(&val, op->data.buf.out + i, op->data.nbytes - i);
>> + val = fsl_qspi_endian_xchg(q, val);
>> + qspi_writel(q, val, base + QUADSPI_TBDR);
>> + }
>> +
>> + if (needs_fill_txfifo(q)) {
>> + for (i = op->data.nbytes; i < 16; i += 4)
>> + qspi_writel(q, 0, base + QUADSPI_TBDR);
>> + }
>> +}
>> +
>> +static void fsl_qspi_read_rxfifo(struct fsl_qspi *q,
>> + const struct spi_mem_op *op)
>> +{
>> + void __iomem *base = q->iobase;
>> + int i;
>> + u8 *buf = op->data.buf.in;
>> + u32 val;
>> +
>> + for (i = 0; i < ALIGN_DOWN(op->data.nbytes, 4); i += 4) {
>> + val = qspi_readl(q, base + QUADSPI_RBDR(i / 4));
>> + val = fsl_qspi_endian_xchg(q, val);
>> + memcpy(buf + i, &val, 4);
>> + }
>> +
>> + if (i < op->data.nbytes) {
>> + val = qspi_readl(q, base + QUADSPI_RBDR(i / 4));
>> + val = fsl_qspi_endian_xchg(q, val);
>> + memcpy(buf + i, &val, op->data.nbytes - i);
>> + }
>> +}
>> +
>> +static int fsl_qspi_do_op(struct fsl_qspi *q, const struct spi_mem_op
>> +*op) {
>> + void __iomem *base = q->iobase;
>> + int err = 0;
>> +
>> + init_completion(&q->c);
>> +
>> + /*
>> + * Always start the sequence at the same index since we update
>> + * the LUT at each exec_op() call. And also specify the DATA
>> + * length, since it's has not been specified in the LUT.
>> + */
>> + qspi_writel(q, op->data.nbytes | QUADSPI_IPCR_SEQID(SEQID_LUT),
>> + base + QUADSPI_IPCR);
>> +
>> + /* Wait for the interrupt. */
>> + if (!wait_for_completion_timeout(&q->c, msecs_to_jiffies(1000)))
>> + err = -ETIMEDOUT;
>> +
>> + if (!err && op->data.nbytes && op->data.dir == SPI_MEM_DATA_IN)
>> + fsl_qspi_read_rxfifo(q, op);
>> +
>> + return err;
>> +}
>> +
>> +static int fsl_qspi_readl_poll_tout(struct fsl_qspi *q, void __iomem *base,
>> + u32 mask, u32 delay_us, u32 timeout_us) {
>> + u32 reg;
>> +
>> + if (!q->devtype_data->little_endian)
>> + mask = (u32)cpu_to_be32(mask);
>> +
>
> reg is being used as an un-initialized variable, didn't it needs to be initialized with some proper value?

No, it does not need to be initialized. This is only to assign some
memory for the readx_poll_timeout() macro: [1].

[1]
https://elixir.bootlin.com/linux/latest/source/include/linux/iopoll.h#L50

>
>> + return readl_poll_timeout(base, reg, !(reg & mask), delay_us,
>> + timeout_us);
>> +}
>> +
>
> --
> Regards
> Yogesh Gaur.
>
> [...]
>

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