Re: [PATCH] nios2: Add Altera SPI master driver

[Hubert Feurstein <h.feurstein@gmail.com>]

Hi Franck,

please fix the errors reported by ./scripts/checkpatch.pl.

@Sascha: What about "WARNING: line over 80 characters". Should we take
care about this warning?

Regards
Hubert

2011/7/30  <franck.jullien@gmail.com>:
> From: Franck Jullien <franck.jullien@gmail.com>
>
> Signed-off-by: Franck Jullien <franck.jullien@gmail.com>
> ---
>  arch/nios2/include/asm/spi.h |   21 ++++
>  drivers/spi/Kconfig          |    5 +
>  drivers/spi/Makefile         |    1 +
>  drivers/spi/altera_spi.c     |  226 ++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 253 insertions(+), 0 deletions(-)
>  create mode 100644 arch/nios2/include/asm/spi.h
>  create mode 100644 drivers/spi/altera_spi.c
>
> diff --git a/arch/nios2/include/asm/spi.h b/arch/nios2/include/asm/spi.h
> new file mode 100644
> index 0000000..4e576b9
> --- /dev/null
> +++ b/arch/nios2/include/asm/spi.h
> @@ -0,0 +1,21 @@
> +#ifndef __ALTERA_SPI_H_
> +#define __ALTERA_SPI_H_
> +
> +#include <spi/spi.h>
> +
> +struct spi_altera_master {
> +       int     num_chipselect;
> +       int     spi_mode;
> +       int     databits;
> +       int     speed;
> +};
> +
> +struct altera_spi {
> +       struct spi_master       master;
> +       int                     databits;
> +       int                     speed;
> +       int                     mode;
> +       void __iomem            *regs;
> +};
> +
> +#endif /*__ALTERA_SPI_H_*/
> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
> index 9ab03f6..c72493c 100644
> --- a/drivers/spi/Kconfig
> +++ b/drivers/spi/Kconfig
> @@ -19,4 +19,9 @@ config DRIVER_SPI_IMX_2_3
>        depends on ARCH_IMX51 || ARCH_IMX53
>        default y
>
> +config DRIVER_SPI_ALTERA
> +       bool "Altera SPI Master driver"
> +       depends on NIOS2
> +       depends on SPI
> +
>  endmenu
> diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
> index b2b2f67..90e141d 100644
> --- a/drivers/spi/Makefile
> +++ b/drivers/spi/Makefile
> @@ -1,2 +1,3 @@
>  obj-$(CONFIG_SPI) += spi.o
>  obj-$(CONFIG_DRIVER_SPI_IMX) += imx_spi.o
> +obj-$(CONFIG_DRIVER_SPI_ALTERA) += altera_spi.o
> diff --git a/drivers/spi/altera_spi.c b/drivers/spi/altera_spi.c
> new file mode 100644
> index 0000000..71df6b7
> --- /dev/null
> +++ b/drivers/spi/altera_spi.c
> @@ -0,0 +1,226 @@
> +/*
> + * (C) Copyright 2011 - Franck JULLIEN <elec4fun@gmail.com>
> + * Inspired from Thomas Chou's Linux spi_altera.c driver
> + *
> + * 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.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with this program; if not, write to the Free Software
> + * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
> + * MA 02111-1307 USA
> + *
> + */
> +
> +#include <common.h>
> +#include <init.h>
> +#include <driver.h>
> +#include <spi/spi.h>
> +#include <asm/io.h>
> +#include <asm/spi.h>
> +#include <asm/nios2-io.h>
> +
> +#define CS_ACTIVE      1
> +#define CS_INACTIVE    0
> +
> +static int altera_spi_setup(struct spi_device *spi)
> +{
> +       struct spi_master *master = spi->master;
> +       struct device_d *master_dev = master->dev;
> +       struct device_d spi_dev = spi->dev;
> +       struct altera_spi *altera_spi = container_of(master, struct altera_spi, master);
> +
> +       if (spi->bits_per_word != altera_spi->databits) {
> +               printf("%s doesn't support %d bits per word requested by %s\n", master_dev->name,
> +                       spi->bits_per_word, spi_dev.name);
> +               return -1;
> +       }
> +
> +       if ((spi->mode & (SPI_CPHA | SPI_CPOL)) != altera_spi->mode) {
> +               printf("%s doesn't support SPI_MODE%d requested by %s\n", master_dev->name,
> +                       spi->mode & (SPI_CPHA | SPI_CPOL), spi_dev.name);
> +               return -1;
> +       }
> +
> +       if (spi->max_speed_hz < altera_spi->speed) {
> +               printf("%s frequency is too high for %s\n", master_dev->name, spi_dev.name);
> +               return -1;
> +       }
> +
> +       debug("%s mode 0x%08x bits_per_word: %d speed: %d\n",
> +                       __func__, spi->mode, spi->bits_per_word,
> +                       altera_spi->speed);
> +
> +       return 0;
> +}
> +
> +
> +static unsigned int altera_spi_xchg_single(struct altera_spi *altera_spi, unsigned int data)
> +{
> +       struct nios_spi *nios_spi = altera_spi->regs;
> +
> +       while (!(readl(&nios_spi->status) & NIOS_SPI_TRDY));
> +       writel(data, &nios_spi->txdata);
> +
> +       while (!(readl(&nios_spi->status) & NIOS_SPI_RRDY));
> +
> +       return readl(&nios_spi->rxdata);
> +}
> +
> +/*
> + * When using SPI_CS_HIGH devices, only one device is allowed to be
> + * connected to the Altera SPI master. This limitation is due to the
> + * emulation of an active high CS by writing 0 to the slaveselect register
> + * (this produce a '1' to all CS pins).
> + */
> +static void altera_spi_chipselect(struct spi_device *spi, int is_active)
> +{
> +       struct altera_spi *altera_spi = container_of(spi->master, struct altera_spi, master);
> +       struct nios_spi *nios_spi = altera_spi->regs;
> +       uint32_t tmp;
> +
> +       if (spi->mode & SPI_CS_HIGH) {
> +               switch (is_active) {
> +               case CS_INACTIVE:
> +                       writel(1 << spi->chip_select, &nios_spi->slaveselect);
> +                       tmp = readl(&nios_spi->control);
> +                       writel(tmp | NIOS_SPI_SSO, &nios_spi->control);
> +                       break;
> +
> +               case CS_ACTIVE:
> +                       tmp = readw(&nios_spi->control);
> +                       writew(tmp & ~NIOS_SPI_SSO, &nios_spi->control);
> +                       writel(0, &nios_spi->slaveselect);
> +                       break;
> +               }
> +       } else {
> +               switch (is_active) {
> +               case CS_INACTIVE:
> +                       tmp = readw(&nios_spi->control);
> +                       writew(tmp & ~NIOS_SPI_SSO, &nios_spi->control);
> +                       break;
> +
> +               case CS_ACTIVE:
> +                       writel(1 << spi->chip_select, &nios_spi->slaveselect);
> +                       tmp = readl(&nios_spi->control);
> +                       writel(tmp | NIOS_SPI_SSO, &nios_spi->control);
> +                       break;
> +               }
> +       }
> +}
> +
> +static int altera_spi_transfer(struct spi_device *spi, struct spi_message *mesg)
> +{
> +       struct altera_spi *altera_spi = container_of(spi->master, struct altera_spi, master);
> +       struct nios_spi *nios_spi = altera_spi->regs;
> +       struct spi_transfer     *t = NULL;
> +       int word_len =  spi->bits_per_word;
> +
> +       u32 txval;
> +       u32 rxval;
> +
> +       altera_spi_chipselect(spi, 1);
> +
> +       word_len = spi->bits_per_word;
> +       mesg->actual_length = 0;
> +
> +       list_for_each_entry(t, &mesg->transfers, transfer_list) {
> +
> +               if (word_len <= 8) {
> +                       const u8 *txbuf = t->tx_buf;
> +                       u8 *rxbuf = t->rx_buf;
> +                       int i = 0;
> +
> +                       while (i < t->len) {
> +                               txval = txbuf ? txbuf[i] : 0;
> +                               rxval = altera_spi_xchg_single(altera_spi, txval);
> +                               if (rxbuf)
> +                                       rxbuf[i] = rxval;
> +                               i++;
> +                               mesg->actual_length++;
> +                       }
> +               } else if (word_len <= 16) {
> +                       const u16 *txbuf = t->tx_buf;
> +                       u16 *rxbuf = t->rx_buf;
> +                       int i = 0;
> +
> +                       while (i < t->len >> 1) {
> +                               txval = txbuf ? txbuf[i] : 0;
> +                               rxval = altera_spi_xchg_single(altera_spi, txval);
> +                               if (rxbuf)
> +                                       rxbuf[i] = rxval;
> +                               i++;
> +                               mesg->actual_length += 2;
> +                       }
> +               } else if (word_len <= 32) {
> +                       const u32 *txbuf = t->tx_buf;
> +                       u32 *rxbuf = t->rx_buf;
> +                       int i = 0;
> +
> +                       while (i < t->len >> 2) {
> +                               txval = txbuf ? txbuf[i] : 0;
> +                               rxval = altera_spi_xchg_single(altera_spi, txval);
> +                               if (rxbuf)
> +                                       rxbuf[i] = rxval;
> +                               i++;
> +                               mesg->actual_length += 4;
> +                       }
> +               }
> +       }
> +
> +       /* Wait the end of any pending transfert */
> +       while ((readl(&nios_spi->status) & NIOS_SPI_TMT) == 0);
> +
> +       altera_spi_chipselect(spi, 0);
> +
> +       return 0;
> +}
> +
> +static int altera_spi_probe(struct device_d *dev)
> +{
> +       struct spi_master *master;
> +       struct altera_spi *altera_spi;
> +       struct spi_altera_master *pdata = dev->platform_data;
> +       struct nios_spi *nios_spi;
> +
> +       altera_spi = xzalloc(sizeof(*altera_spi));
> +
> +       master = &altera_spi->master;
> +       master->dev = dev;
> +
> +       master->setup = altera_spi_setup;
> +       master->transfer = altera_spi_transfer;
> +       master->num_chipselect = pdata->num_chipselect;
> +
> +       altera_spi->regs = dev_request_mem_region(dev, 0);
> +       altera_spi->databits = pdata->databits;
> +       altera_spi->speed = pdata->speed;
> +       altera_spi->mode = pdata->spi_mode;
> +
> +       nios_spi = altera_spi->regs;
> +       writel(0, &nios_spi->slaveselect);
> +       writel(0, &nios_spi->control);
> +
> +       spi_register_master(master);
> +
> +       return 0;
> +}
> +
> +static struct driver_d altera_spi_driver = {
> +       .name  = "altera_spi",
> +       .probe = altera_spi_probe,
> +};
> +
> +static int altera_spi_driver_init(void)
> +{
> +       return register_driver(&altera_spi_driver);
> +}
> +
> +device_initcall(altera_spi_driver_init);
> --
> 1.7.6
>
>
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