Re: [PATCH v2] spi: New driver for Altera SPI

[Grant Likely <grant.likely-s3s/WqlpOiPyB63q8FvJNQ@public.gmane.org>]

On Sun, Jan 16, 2011 at 10:46 PM, Thomas Chou <thomas-SDxUXYEhEBiCuPEqFHbRBg@public.gmane.org> wrote:
> This patch adds a new SPI driver to support the Altera SOPC Builder
> SPI component. It uses the bitbanging library.
>
> Signed-off-by: Thomas Chou <thomas-SDxUXYEhEBiCuPEqFHbRBg@public.gmane.org>

Hi Thomas, some minor comments below.  I've not dug any deeper, so I
have not verified locking or the way the driver uses the bitbang
library, or anything like that.

g.

> ---
> v2 add devicetree support.
>
>  drivers/spi/Kconfig            |    6 +
>  drivers/spi/Makefile           |    1 +
>  drivers/spi/spi_altera.c       |  398 ++++++++++++++++++++++++++++++++++++++++
>  include/linux/spi/spi_altera.h |   12 ++
>  4 files changed, 417 insertions(+), 0 deletions(-)
>  create mode 100644 drivers/spi/spi_altera.c
>  create mode 100644 include/linux/spi/spi_altera.h
>
> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
> index 13bfa9d..2b5b8d6 100644
> --- a/drivers/spi/Kconfig
> +++ b/drivers/spi/Kconfig
> @@ -53,6 +53,12 @@ if SPI_MASTER
>
>  comment "SPI Master Controller Drivers"
>
> +config SPI_ALTERA
> +       tristate "Altera SPI Controller"
> +       select SPI_BITBANG
> +       help
> +         This is the driver for the Altera SPI Controller.
> +
>  config SPI_ATMEL
>        tristate "Atmel SPI Controller"
>        depends on (ARCH_AT91 || AVR32)
> diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
> index 3a42463..c2675a4 100644
> --- a/drivers/spi/Makefile
> +++ b/drivers/spi/Makefile
> @@ -9,6 +9,7 @@ ccflags-$(CONFIG_SPI_DEBUG) := -DDEBUG
>  obj-$(CONFIG_SPI_MASTER)               += spi.o
>
>  # SPI master controller drivers (bus)
> +obj-$(CONFIG_SPI_ALTERA)               += spi_altera.o
>  obj-$(CONFIG_SPI_ATMEL)                        += atmel_spi.o
>  obj-$(CONFIG_SPI_BFIN)                 += spi_bfin5xx.o
>  obj-$(CONFIG_SPI_BITBANG)              += spi_bitbang.o
> diff --git a/drivers/spi/spi_altera.c b/drivers/spi/spi_altera.c
> new file mode 100644
> index 0000000..28c78c3
> --- /dev/null
> +++ b/drivers/spi/spi_altera.c
> @@ -0,0 +1,398 @@
> +/*
> + * Altera SPI driver
> + *
> + * Copyright (C) 2008 Thomas Chou <thomas-SDxUXYEhEBiCuPEqFHbRBg@public.gmane.org>
> + *
> + * Based on spi_s3c24xx.c, which is:
> + * Copyright (c) 2006 Ben Dooks
> + * Copyright (c) 2006 Simtec Electronics
> + *     Ben Dooks <ben-Y5A6D6n0/KfQXOPxS62xeg@public.gmane.org>
> + *
> + * 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.
> + */
> +
> +#include <linux/init.h>
> +#include <linux/spinlock.h>
> +#include <linux/workqueue.h>
> +#include <linux/interrupt.h>
> +#include <linux/delay.h>
> +#include <linux/errno.h>
> +#include <linux/err.h>
> +#include <linux/clk.h>
> +#include <linux/platform_device.h>
> +#include <linux/spi/spi.h>
> +#include <linux/spi/spi_bitbang.h>
> +#include <linux/spi/spi_altera.h>
> +#include <linux/io.h>
> +#include <linux/of.h>
> +
> +#define DRV_NAME "spi_altera"
> +
> +#define ALTERA_SPI_RXDATA      0
> +#define ALTERA_SPI_TXDATA      4
> +#define ALTERA_SPI_STATUS      8
> +#define ALTERA_SPI_CONTROL     12
> +#define ALTERA_SPI_SLAVE_SEL   20
> +
> +#define ALTERA_SPI_STATUS_ROE_MSK      0x8
> +#define ALTERA_SPI_STATUS_TOE_MSK      0x10
> +#define ALTERA_SPI_STATUS_TMT_MSK      0x20
> +#define ALTERA_SPI_STATUS_TRDY_MSK     0x40
> +#define ALTERA_SPI_STATUS_RRDY_MSK     0x80
> +#define ALTERA_SPI_STATUS_E_MSK                0x100
> +
> +#define ALTERA_SPI_CONTROL_IROE_MSK    0x8
> +#define ALTERA_SPI_CONTROL_ITOE_MSK    0x10
> +#define ALTERA_SPI_CONTROL_ITRDY_MSK   0x40
> +#define ALTERA_SPI_CONTROL_IRRDY_MSK   0x80
> +#define ALTERA_SPI_CONTROL_IE_MSK      0x100
> +#define ALTERA_SPI_CONTROL_SSO_MSK     0x400
> +
> +struct altera_spi {
> +       /* bitbang has to be first */
> +       struct spi_bitbang bitbang;
> +       struct completion done;
> +
> +       void __iomem *base;
> +       int irq;
> +       int interrupt; /* use interrupt driven data transfer, slow */

Is this a flag?  If so, use type 'bool'.

> +       int len;
> +       int count;
> +       int bytes_per_word;
> +       unsigned long imr;
> +
> +       /* data buffers */
> +       const unsigned char *tx;
> +       unsigned char *rx;
> +
> +};

Nit: drop the blank line at the end of the structure.

> +
> +static inline struct altera_spi *to_hw(struct spi_device *sdev)

All file scope symbols should have a driver prefix.  In this case, it
should be "altera_spi_to_hw()".

> +{
> +       return spi_master_get_devdata(sdev->master);
> +}
> +
> +static void altera_spi_chipsel(struct spi_device *spi, int value)
> +{
> +       struct altera_spi *hw = to_hw(spi);
> +
> +       if (spi->mode & SPI_CS_HIGH) {
> +               switch (value) {
> +               case BITBANG_CS_INACTIVE:
> +                       writel(1 << spi->chip_select,
> +                              hw->base + ALTERA_SPI_SLAVE_SEL);
> +                       hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
> +                       writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
> +                       break;
> +
> +               case BITBANG_CS_ACTIVE:
> +                       hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
> +                       writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
> +                       writel(0, hw->base + ALTERA_SPI_SLAVE_SEL);
> +                       break;
> +               }
> +       } else {
> +               switch (value) {
> +               case BITBANG_CS_INACTIVE:
> +                       hw->imr &= ~ALTERA_SPI_CONTROL_SSO_MSK;
> +                       writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
> +                       break;
> +
> +               case BITBANG_CS_ACTIVE:
> +                       writel(1 << spi->chip_select,
> +                              hw->base + ALTERA_SPI_SLAVE_SEL);
> +                       hw->imr |= ALTERA_SPI_CONTROL_SSO_MSK;
> +                       writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
> +                       break;
> +               }
> +       }
> +}
> +
> +static int altera_spi_setupxfer(struct spi_device *spi, struct spi_transfer *t)
> +{
> +       return 0;
> +}
> +
> +static int altera_spi_setup(struct spi_device *spi)
> +{
> +       return 0;
> +}
> +
> +static inline unsigned int hw_txbyte(struct altera_spi *hw, int count)
> +{
> +       if (hw->tx) {
> +               switch (hw->bytes_per_word) {
> +               case 1:
> +                       return hw->tx[count];
> +               case 2:
> +                       return (hw->tx[count * 2]
> +                               | (hw->tx[count * 2 + 1] << 8));
> +               }
> +       }
> +
> +       return 0;
> +}
> +
> +static int altera_spi_txrx(struct spi_device *spi, struct spi_transfer *t)
> +{
> +       struct altera_spi *hw = to_hw(spi);
> +
> +       hw->tx = t->tx_buf;
> +       hw->rx = t->rx_buf;
> +       hw->count = 0;
> +       hw->bytes_per_word = (t->bits_per_word ? : spi->bits_per_word) / 8;
> +       hw->len = t->len / hw->bytes_per_word;
> +
> +       if (hw->irq >= 0 && hw->interrupt) {
> +               init_completion(&hw->done);
> +               /* enable receive interrupt */
> +               hw->imr |= ALTERA_SPI_CONTROL_IRRDY_MSK;
> +               writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
> +
> +               /* send the first byte */
> +               writel(hw_txbyte(hw, 0), hw->base + ALTERA_SPI_TXDATA);
> +
> +               wait_for_completion(&hw->done);
> +               /* disable receive interrupt */
> +               hw->imr &= ~ALTERA_SPI_CONTROL_IRRDY_MSK;
> +               writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
> +       } else {
> +               /* send the first byte */
> +               writel(hw_txbyte(hw, 0), hw->base + ALTERA_SPI_TXDATA);
> +
> +               while (1) {
> +                       unsigned int rxd;
> +
> +                       while (!(readl(hw->base + ALTERA_SPI_STATUS) &
> +                                ALTERA_SPI_STATUS_RRDY_MSK))
> +                               cpu_relax();
> +
> +                       rxd = readl(hw->base + ALTERA_SPI_RXDATA);
> +                       if (hw->rx) {
> +                               switch (hw->bytes_per_word) {
> +                               case 1:
> +                                       hw->rx[hw->count] = rxd;
> +                                       break;
> +                               case 2:
> +                                       hw->rx[hw->count * 2] = rxd;
> +                                       hw->rx[hw->count * 2 + 1] = rxd >> 8;
> +                                       break;
> +                               }
> +                       }
> +
> +                       hw->count++;
> +
> +                       if (hw->count < hw->len)
> +                               writel(hw_txbyte(hw, hw->count),
> +                                      hw->base + ALTERA_SPI_TXDATA);
> +                       else
> +                               break;
> +               }
> +
> +       }
> +
> +       return hw->count * hw->bytes_per_word;
> +}
> +
> +static irqreturn_t altera_spi_irq(int irq, void *dev)
> +{
> +       struct altera_spi *hw = dev;
> +       unsigned int rxd;
> +
> +       rxd = readl(hw->base + ALTERA_SPI_RXDATA);
> +       if (hw->rx) {
> +               switch (hw->bytes_per_word) {
> +               case 1:
> +                       hw->rx[hw->count] = rxd;
> +                       break;
> +               case 2:
> +                       hw->rx[hw->count * 2] = rxd;
> +                       hw->rx[hw->count * 2 + 1] = rxd >> 8;
> +                       break;
> +               }
> +       }
> +
> +       hw->count++;
> +
> +       if (hw->count < hw->len)
> +               writel(hw_txbyte(hw, hw->count), hw->base + ALTERA_SPI_TXDATA);
> +       else
> +               complete(&hw->done);
> +
> +       return IRQ_HANDLED;
> +}
> +
> +#ifdef CONFIG_OF
> +static int __devinit altera_spi_of_probe(struct platform_device *pdev,
> +                                      struct altera_spi *hw)
> +{
> +       const __be32 *val;
> +
> +       hw->bitbang.master->dev.of_node = pdev->dev.of_node;
> +       val = of_get_property(pdev->dev.of_node, "interrupt-driven", NULL);
> +       if (val)
> +               hw->interrupt = be32_to_cpup(val);
> +       return 0;
> +}
> +#else
> +static int __devinit altera_spi_of_probe(struct platform_device *pdev,
> +                                      struct altera_spi *hw)
> +{
> +       return 0;
> +}
> +#endif
> +
> +static int __devinit altera_spi_probe(struct platform_device *pdev)
> +{
> +       struct altera_spi_platform_data *platp = pdev->dev.platform_data;
> +       struct altera_spi *hw;
> +       struct spi_master *master;
> +       struct resource *res;
> +       int err = 0;
> +
> +       master = spi_alloc_master(&pdev->dev, sizeof(struct altera_spi));
> +       if (master == NULL) {
> +               dev_err(&pdev->dev, "No memory for spi_master\n");
> +               err = -ENOMEM;
> +               goto err_no_mem;
> +       }
> +
> +       /* setup the master state. */
> +       master->bus_num = pdev->id;
> +       master->num_chipselect = 16;
> +       master->mode_bits = SPI_CS_HIGH;
> +       master->setup = altera_spi_setup;
> +
> +       hw = spi_master_get_devdata(master);
> +       platform_set_drvdata(pdev, hw);
> +
> +       /* setup the state for the bitbang driver */
> +       hw->bitbang.master = spi_master_get(master);
> +       if (hw->bitbang.master == NULL) {
> +               dev_err(&pdev->dev, "Cannot get device\n");
> +               err = -ENODEV;
> +               goto err_no_dev;
> +       }
> +       hw->bitbang.setup_transfer = altera_spi_setupxfer;
> +       hw->bitbang.chipselect = altera_spi_chipsel;
> +       hw->bitbang.txrx_bufs = altera_spi_txrx;
> +
> +       /* find and map our resources */
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       if (res == NULL) {
> +               dev_err(&pdev->dev, "Cannot get IORESOURCE_MEM\n");
> +               err = -ENOENT;
> +               goto err_no_iores;
> +       }
> +       hw->base = ioremap(res->start, (res->end - res->start) + 1);
> +       if (hw->base == 0) {
> +               dev_err(&pdev->dev, "Cannot map IO\n");
> +               err = -ENXIO;
> +               goto err_no_iomap;
> +       }
> +       /* program defaults into the registers */
> +       hw->imr = 0;            /* disable spi interrupts */
> +       writel(hw->imr, hw->base + ALTERA_SPI_CONTROL);
> +       writel(0, hw->base + ALTERA_SPI_STATUS);        /* clear status reg */
> +       if (readl(hw->base + ALTERA_SPI_STATUS) & ALTERA_SPI_STATUS_RRDY_MSK)
> +               readl(hw->base + ALTERA_SPI_RXDATA);    /* flush rxdata */
> +       /* irq is optional */
> +       hw->irq = platform_get_irq(pdev, 0);
> +       if (hw->irq >= 0) {
> +               init_completion(&hw->done);
> +               err = request_irq(hw->irq, altera_spi_irq, 0, pdev->name, hw);
> +               if (err) {
> +                       dev_err(&pdev->dev, "Cannot claim IRQ\n");
> +                       goto err_no_irq;
> +               }
> +       }
> +       /* find platform data */
> +       if (platp) {
> +               hw->interrupt = platp->interrupt;
> +       } else {
> +               err = altera_spi_of_probe(pdev, hw);
> +               if (err)
> +                       goto err_no_of;
> +       }
> +
> +       /* register our spi controller */
> +       err = spi_bitbang_start(&hw->bitbang);
> +       if (err) {
> +               dev_err(&pdev->dev, "Failed to register SPI master\n");
> +               goto err_register;
> +       }
> +       dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
> +
> +       return 0;
> +
> +err_register:
> +err_no_of:
> +       if (hw->irq >= 0)
> +               free_irq(hw->irq, hw);
> +err_no_irq:
> +       iounmap((void *)hw->base);

The cast should not be necessary.

> +err_no_iomap:
> +err_no_iores:
> +       spi_master_put(master);;
> +err_no_mem:
> +err_no_dev:
> +       return err;
> +}
> +
> +static int __devexit altera_spi_remove(struct platform_device *dev)
> +{
> +       struct altera_spi *hw = platform_get_drvdata(dev);
> +       struct spi_master *master = hw->bitbang.master;
> +
> +       spi_bitbang_stop(&hw->bitbang);
> +
> +       if (hw->irq >= 0)
> +               free_irq(hw->irq, hw);
> +       iounmap((void *)hw->base);

Ditto here.

> +
> +       platform_set_drvdata(dev, NULL);
> +       spi_master_put(master);
> +       return 0;
> +}
> +
> +#ifdef CONFIG_OF
> +static struct of_device_id altera_spi_match[] = {
> +       {
> +               .compatible = "altera,spi_altera",
> +       },
> +       {},
> +}
> +MODULE_DEVICE_TABLE(of, altera_spi_match);
> +#endif
> +
> +static struct platform_driver altera_spidrv = {
> +       .remove = __devexit_p(altera_spi_remove),
> +       .driver = {
> +               .name = DRV_NAME,
> +               .owner = THIS_MODULE,
> +               .pm = NULL,
> +#ifdef CONFIG_OF
> +               .of_match_table = altera_spi_match,
> +#endif
> +       },
> +};
> +
> +static int __init altera_spi_init(void)
> +{
> +       return platform_driver_probe(&altera_spidrv, altera_spi_probe);
> +}
> +
> +static void __exit altera_spi_exit(void)
> +{
> +       platform_driver_unregister(&altera_spidrv);
> +}
> +
> +module_init(altera_spi_init);

Move module_init line to be immediately after altera_spi_init() definition.

> +module_exit(altera_spi_exit);
> +
> +MODULE_DESCRIPTION("Altera SPI driver");
> +MODULE_AUTHOR("Thomas Chou <thomas-SDxUXYEhEBiCuPEqFHbRBg@public.gmane.org>");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:" DRV_NAME);
> diff --git a/include/linux/spi/spi_altera.h b/include/linux/spi/spi_altera.h
> new file mode 100644
> index 0000000..b3d7f69
> --- /dev/null
> +++ b/include/linux/spi/spi_altera.h
> @@ -0,0 +1,12 @@
> +#ifndef _LINUX_SPI_SPI_ALTERA_H
> +#define _LINUX_SPI_SPI_ALTERA_H
> +
> +/*
> + * struct altera_spi_platform_data - platform data of the Altera SPI
> + * @interrupt: use intrrupt driven data transfer.
> + */
> +struct altera_spi_platform_data {
> +       int interrupt;
> +};
> +
> +#endif /* _LINUX_SPI_SPI_ALTERA_H */
> --
> 1.7.3.4
>
>



-- 
Grant Likely, B.Sc., P.Eng.
Secret Lab Technologies Ltd.