Re: [PATCHv2] drivers: spi: Add qspi flash controller

From: Felipe Balbi
Date: Tue Jul 02 2013 - 05:25:21 EST

Hi,

On Tue, Jul 02, 2013 at 02:26:39PM +0530, Sourav Poddar wrote:
> diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
> index 33f9c09..ea14eff 100644
> --- a/drivers/spi/Makefile
> +++ b/drivers/spi/Makefile
> @@ -46,6 +46,7 @@ obj-$(CONFIG_SPI_OCTEON) += spi-octeon.o
> obj-$(CONFIG_SPI_OMAP_UWIRE) += spi-omap-uwire.o
> obj-$(CONFIG_SPI_OMAP_100K) += spi-omap-100k.o
> obj-$(CONFIG_SPI_OMAP24XX) += spi-omap2-mcspi.o
> +obj-$(CONFIG_QSPI_DRA7xxx) += ti-qspi.o

all other drivers are prepended with spi-

> diff --git a/drivers/spi/ti-qspi.c b/drivers/spi/ti-qspi.c
> new file mode 100644
> index 0000000..e646a93
> --- /dev/null
> +++ b/drivers/spi/ti-qspi.c
> @@ -0,0 +1,357 @@
> +/*
> + * TI QSPI driver
> + *
> + * Copyright (C) 2013, Texas Instruments, Incorporated
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License as
> + * published by the Free Software Foundation; either version 2 of
> + * the License, or (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR /PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/init.h>
> +#include <linux/interrupt.h>
> +#include <linux/module.h>
> +#include <linux/device.h>
> +#include <linux/delay.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/dmaengine.h>
> +#include <linux/omap-dma.h>
> +#include <linux/platform_device.h>
> +#include <linux/err.h>
> +#include <linux/clk.h>
> +#include <linux/io.h>
> +#include <linux/slab.h>
> +#include <linux/pm_runtime.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/pinctrl/consumer.h>
> +
> +#include <linux/spi/spi.h>
> +
> +struct dra7xxx_qspi {
> + struct spi_master *master;
> + void __iomem *base;
> + int device_type;
> + struct device *dev;

nit: move this pointer up and the int down.

> + u32 spi_max_frequency;
> + u32 cmd;
> + u32 dc;
> +};
> +
> +#define QSPI_PID (0x0)
> +#define QSPI_SYSCONFIG (0x10)
> +#define QSPI_INTR_STATUS_RAW_SET (0x20)
> +#define QSPI_INTR_STATUS_ENABLED_CLEAR (0x24)
> +#define QSPI_INTR_ENABLE_SET_REG (0x28)
> +#define QSPI_INTR_ENABLE_CLEAR_REG (0x2c)
> +#define QSPI_SPI_CLOCK_CNTRL_REG (0x40)
> +#define QSPI_SPI_DC_REG (0x44)
> +#define QSPI_SPI_CMD_REG (0x48)
> +#define QSPI_SPI_STATUS_REG (0x4c)
> +#define QSPI_SPI_DATA_REG (0x50)
> +#define QSPI_SPI_SETUP0_REG (0x54)
> +#define QSPI_SPI_SWITCH_REG (0x64)
> +#define QSPI_SPI_SETUP1_REG (0x58)
> +#define QSPI_SPI_SETUP2_REG (0x5c)
> +#define QSPI_SPI_SETUP3_REG (0x60)
> +#define QSPI_SPI_DATA_REG_1 (0x68)
> +#define QSPI_SPI_DATA_REG_2 (0x6c)
> +#define QSPI_SPI_DATA_REG_3 (0x70)
> +
> +#define QSPI_TIMEOUT 2000000
> +
> +#define QSPI_FCLK 192000000
> +
> +/* Clock Control */
> +#define QSPI_CLK_EN (1 << 31)
> +#define QSPI_CLK_DIV_MAX 0xffff
> +
> +/* Command */
> +#define QSPI_EN_CS(n) (n << 28)
> +#define QSPI_WLEN(n) ((n-1) << 19)
> +#define QSPI_3_PIN (1 << 18)
> +#define QSPI_RD_SNGL (1 << 16)
> +#define QSPI_WR_SNGL (2 << 16)
> +#define QSPI_RD_QUAD (7 << 16)
> +#define QSPI_INVAL (4 << 16)
> +
> +/* Device Control */
> +#define QSPI_DD(m, n) (m << (3 + n*8))
> +#define QSPI_CKPHA(n) (1 << (2 + n*8))
> +#define QSPI_CSPOL(n) (1 << (1 + n*8))
> +#define QSPI_CKPOL(n) (1 << (n*8))
> +
> +/* Status */
> +#define QSPI_WC (1 << 1)
> +#define QSPI_BUSY (1 << 0)
> +#define QSPI_WC_BUSY (QSPI_WC | QSPI_BUSY)
> +#define QSPI_XFER_DONE QSPI_WC
> +
> +#define XFER_END 0x01
> +
> +#define SPI_AUTOSUSPEND_TIMEOUT 2000
> +
> +static inline unsigned long dra7xxx_readl(struct dra7xxx_qspi *qspi,
> + unsigned long reg)
> +{
> + return readl(qspi->base + reg);
> +}
> +
> +static inline void dra7xxx_writel(struct dra7xxx_qspi *qspi,
> + unsigned long val, unsigned long reg)
> +{
> + writel(val, qspi->base + reg);
> +}
> +
> +static int dra7xxx_qspi_setup(struct spi_device *spi)
> +{
> + struct dra7xxx_qspi *qspi =
> + spi_master_get_devdata(spi->master);
> +
> + int clk_div;
> +
> + if (!qspi->spi_max_frequency)
> + clk_div = 0;

won't this generate division by zero ?

> + else
> + clk_div = (QSPI_FCLK / qspi->spi_max_frequency) - 1;

this QSPI_FCLK looks like it should be a clk_get_rate().

> + pr_debug("%s: hz: %d, clock divider %d\n", __func__,
> + qspi->spi_max_frequency, clk_div);

dev_dbg()

> + pm_runtime_get_sync(qspi->dev);
> +
> + /* disable SCLK */
> + dra7xxx_writel(qspi, dra7xxx_readl(qspi, QSPI_SPI_CLOCK_CNTRL_REG)
> + & ~QSPI_CLK_EN, QSPI_SPI_CLOCK_CNTRL_REG);
> +
> + if (clk_div < 0) {
> + pr_debug("%s: clock divider < 0, using /1 divider\n", __func__);
> + clk_div = 0;
> + }
> +
> + if (clk_div > QSPI_CLK_DIV_MAX) {
> + pr_debug("%s: clock divider >%d , using /%d divider\n",
> + __func__, QSPI_CLK_DIV_MAX, QSPI_CLK_DIV_MAX + 1);
> + clk_div = QSPI_CLK_DIV_MAX;
> + }
> +
> + /* enable SCLK */
> + dra7xxx_writel(qspi, QSPI_CLK_EN | clk_div, QSPI_SPI_CLOCK_CNTRL_REG);
> +
> + pm_runtime_mark_last_busy(qspi->dev);
> + pm_runtime_put_autosuspend(qspi->dev);
> +
> + pr_debug("%s: spi_clock_cntrl %ld\n", __func__,
> + dra7xxx_readl(qspi, QSPI_SPI_CLOCK_CNTRL_REG));

dev_dbg(), also use a cached value of the control register. Read only
once.

> +
> + return 0;
> +}
> +
> +static int dra7xxx_qspi_prepare_xfer(struct spi_master *master)
> +{
> + struct dra7xxx_qspi *qspi = spi_master_get_devdata(master);
> +
> + pm_runtime_get_sync(qspi->dev);
> +
> + return 0;
> +}
> +
> +static int dra7xxx_qspi_unprepare_xfer(struct spi_master *master)
> +{
> + struct dra7xxx_qspi *qspi = spi_master_get_devdata(master);
> +
> + pm_runtime_mark_last_busy(qspi->dev);
> + pm_runtime_put_autosuspend(qspi->dev);
> +
> + return 0;
> +}
> +
> +static int qspi_transfer_msg(struct dra7xxx_qspi *qspi, unsigned count,
> + const u8 *txbuf, u8 *rxbuf, bool flags)
> +{
> + uint status;
> + int timeout;
> +
> + while (count--) {
> + if (txbuf) {
> + pr_debug("tx cmd %08x dc %08x data %02x\n",
> + qspi->cmd | QSPI_WR_SNGL, qspi->dc, *txbuf);

dev_dbg()

> + dra7xxx_writel(qspi, *txbuf++, QSPI_SPI_DATA_REG);
> + dra7xxx_writel(qspi, qspi->dc, QSPI_SPI_DC_REG);
> + dra7xxx_writel(qspi, qspi->cmd | QSPI_WR_SNGL,
> + QSPI_SPI_CMD_REG);
> + status = dra7xxx_readl(qspi, QSPI_SPI_STATUS_REG);
> + timeout = QSPI_TIMEOUT;
> + while ((status & QSPI_WC_BUSY) != QSPI_XFER_DONE) {

do you really need to poll ? No IRQ available ?

> + if (--timeout < 0) {
> + pr_debug("QSPI tx timed out\n");

dev_dbg()

> + return -1;
> + }
> + status = dra7xxx_readl(qspi, QSPI_SPI_STATUS_REG);
> + }
> + pr_debug("tx done, status %08x\n", status);

dev_dbg()

> + }
> + if (rxbuf) {
> + pr_debug("rx cmd %08x dc %08x\n",
> + qspi->cmd | QSPI_RD_SNGL, qspi->dc);

dev_dbg()

> + dra7xxx_writel(qspi, qspi->dc, QSPI_SPI_DC_REG);
> + dra7xxx_writel(qspi, qspi->cmd | QSPI_RD_SNGL,
> + QSPI_SPI_CMD_REG);
> + status = dra7xxx_readl(qspi, QSPI_SPI_STATUS_REG);
> + timeout = QSPI_TIMEOUT;
> + while ((status & QSPI_WC_BUSY) != QSPI_XFER_DONE) {
> + if (--timeout < 0) {
> + pr_debug("QSPI rx timed out\n");

dev_dbg()

> + return -1;
> + }
> + status = dra7xxx_readl(qspi, QSPI_SPI_STATUS_REG);
> + }
> + *rxbuf++ = dra7xxx_readl(qspi, QSPI_SPI_DATA_REG);
> + pr_debug("rx done, status %08x, read %02x\n",
> + status, *(rxbuf-1));

dev_dbg()

> + }
> + }
> +
> + if (flags & XFER_END)
> + dra7xxx_writel(qspi, qspi->cmd | QSPI_INVAL, QSPI_SPI_CMD_REG);
> +
> + return 0;
> +}
> +
> +static int dra7xxx_qspi_start_transfer_one(struct spi_master *master,
> + struct spi_message *m)
> +{
> + struct dra7xxx_qspi *qspi = spi_master_get_devdata(master);
> + struct spi_device *spi = m->spi;
> + struct spi_transfer *t;
> + int status = 0;
> + int flags = 0;
> +
> + /* setup command reg */
> + qspi->cmd = 0;
> + qspi->cmd |= QSPI_WLEN(8);
> + qspi->cmd |= QSPI_EN_CS(0);
> + qspi->cmd |= 0xfff;

what is this magic number ???

> + /* setup device control reg */
> + qspi->dc = 0;
> +
> + if (spi->mode & SPI_CPHA)
> + qspi->dc |= QSPI_CKPHA(0);
> + if (spi->mode & SPI_CPOL)
> + qspi->dc |= QSPI_CKPOL(0);
> + if (spi->mode & SPI_CS_HIGH)
> + qspi->dc |= QSPI_CSPOL(0);
> +
> + list_for_each_entry(t, &m->transfers, transfer_list) {
> + if (list_is_last(&t->transfer_list, &m->transfers))
> + flags = XFER_END;
> +
> + qspi_transfer_msg(qspi, t->len, t->tx_buf,
> + t->rx_buf, flags);
> +
> + m->actual_length += t->len;
> + }
> + m->status = status;
> + spi_finalize_current_message(master);
> +
> + return status;
> +}
> +
> +static const struct of_device_id dra7xxx_qspi_match[] = {
> + {.compatible = "ti,dra7xxx-qspi" },
> + {},
> +};
> +MODULE_DEVICE_TABLE(of, dra7xxx_qspi_match);
> +
> +static int dra7xxx_qspi_probe(struct platform_device *pdev)
> +{
> + struct dra7xxx_qspi *qspi;
> + struct spi_master *master;
> + struct resource *r;
> + struct device_node *np = pdev->dev.of_node;
> + u32 max_freq;
> + int ret;
> +
> + master = spi_alloc_master(&pdev->dev, sizeof(*qspi));
> + if (!master)
> + return -ENOMEM;
> +
> + master->mode_bits = SPI_CPOL | SPI_CPHA;
> +
> + master->num_chipselect = 1;
> + master->bus_num = -1;
> + master->setup = dra7xxx_qspi_setup;
> + master->prepare_transfer_hardware = dra7xxx_qspi_prepare_xfer;
> + master->transfer_one_message = dra7xxx_qspi_start_transfer_one;
> + master->unprepare_transfer_hardware = dra7xxx_qspi_unprepare_xfer;
> + master->dev.of_node = pdev->dev.of_node;
> + master->bits_per_word_mask = BIT(32 - 1) | BIT(16 - 1) | BIT(8 - 1);
> +
> + dev_set_drvdata(&pdev->dev, master);
> +
> + qspi = spi_master_get_devdata(master);
> + qspi->master = master;
> + qspi->dev = &pdev->dev;
> +
> + r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + if (r == NULL) {
> + ret = -ENODEV;
> + goto free_master;
> + }
> +
> + qspi->base = devm_ioremap_resource(&pdev->dev, r);
> + if (!qspi->base) {
> + dev_dbg(&pdev->dev, "can't ioremap MCSPI\n");

no need to print anything, devm_ioremap_resource() already prints error
messages.

--
balbi

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