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Date: Sun, 16 Jan 2011 23:56:35 -0700
From: Grant Likely <grant.likely@...retlab.ca>
To: Thomas Chou <thomas@...ron.com.tw>
Cc: David Brownell <dbrownell@...rs.sourceforge.net>,
linux-kernel@...r.kernel.org, nios2-dev@...c.et.ntust.edu.tw,
devicetree-discuss@...ts.ozlabs.org,
spi-devel-general@...ts.sourceforge.net,
Mike Frysinger <vapier@...too.org>
Subject: Re: [PATCH v2] spi: New driver for Altera SPI
On Sun, Jan 16, 2011 at 10:46 PM, Thomas Chou <thomas@...ron.com.tw> 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@...ron.com.tw>
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@...ron.com.tw>
> + *
> + * Based on spi_s3c24xx.c, which is:
> + * Copyright (c) 2006 Ben Dooks
> + * Copyright (c) 2006 Simtec Electronics
> + * Ben Dooks <ben@...tec.co.uk>
> + *
> + * 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@...ron.com.tw>");
> +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.
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