by Ryan Mallon

[permalink] [raw]

Subject: Re: [PATCH v9] spi: New driver for Altera SPI

On 16/02/11 08:42, Grant Likely wrote:
> On Tue, Feb 15, 2011 at 03:04:49PM +0800, Thomas Chou wrote:
>> Dear Ryan,
>>
>> On 02/14/2011 10:20 AM, Ryan Mallon wrote:
>>> On 02/14/2011 03:10 PM, Thomas Chou 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<[email protected]>
>>>> ---
>>>> +struct altera_spi {
>>>> + /* bitbang has to be first */
>>>> + struct spi_bitbang bitbang;
>>> Is this still true? I had a quick look and can't see anything which
>>> relies on spi_bitbang being the first entry. Things like this should be
>>> using container_of so that position in the struct is irrelevant.
>>>
>>> ~Ryan
>>>
>> Yes, sadly true. This is due to the implementation of the bitbanging
>> library, spi_bitbang.c, which assumes the struct spi_bitbang is the
>> first of drvdata. Though it could be changed in the future (beyond
>> this little driver), every bitbanging library user has to follow
>> this for now.
> Should be easy to fix if it is indeed still true (I haven't dug deep
> enough to find the design error yet). Anybody want to volunteer?
>
> g.
>
The problem is that spi_master_get_devdata is used to get both
struct spi_bitbang and the controller dependent structure, which means
that struct spi_bitbang must be the first entry in the container
structure.

The following incomplete, untested patch shows a possible way to fix
this by introducing spi_alloc_master_bitbang. spi_master_get_devdata
now returns a pointer to struct spi_bitbang only. Drivers which need
an additional container struct should allocate it themselves and
pass the bitbang field to spi_alloc_master_bitbang. The driver
specific container can be fetched with:

static inline struct my_spi *to_my_spi(struct spi_master *master)
{
struct spi_bitbang *bitbang = spi_master_get_devdata(master);
return container_of(bitbang, struct my_spi, bitbang);
}

This patch only adds the alloc function and shows the necessary
changes to the spi_gpio.c driver, which is actually pretty minimal.
If there is any interest I can code up a proper patch.

~Ryan

---
diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index 34bb17f..52ec691 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -27,6 +27,7 @@
#include <linux/slab.h>
#include <linux/mod_devicetable.h>
#include <linux/spi/spi.h>
+#include <linux/spi/spi_bitbang.h>
#include <linux/of_spi.h>
#include <linux/pm_runtime.h>

@@ -560,6 +561,24 @@ struct spi_master *spi_alloc_master(struct device *dev, unsigned size)
}
EXPORT_SYMBOL_GPL(spi_alloc_master);

+struct spi_master *spi_alloc_master_bitbang(struct device *dev,
+ struct spi_bitbang *bitbang)
+{
+ struct spi_master *master;
+
+ master = kzalloc(sizeof(struct spi_master), GFP_KERNEL);
+ if (!master)
+ return NULL;
+
+ device_initialize(&master->dev);
+ master->dev.class = &spi_master_class;
+ master->dev.parent = get_device(dev);
+ spi_master_set_devdata(master, bitbang);
+
+ return master;
+}
+EXPORT_SYMBOL_GPL(spi_alloc_master_bitbang);
+
/**
* spi_register_master - register SPI master controller
* @master: initialized master, originally from spi_alloc_master()
diff --git a/drivers/spi/spi_gpio.c b/drivers/spi/spi_gpio.c
index 63e51b0..169dbf0 100644
--- a/drivers/spi/spi_gpio.c
+++ b/drivers/spi/spi_gpio.c
@@ -329,12 +329,17 @@ static int __init spi_gpio_probe(struct platform_device *pdev)
if (status < 0)
return status;

- master = spi_alloc_master(&pdev->dev, sizeof *spi_gpio);
- if (!master) {
+ spi_gpio = kzalloc(sizeof(struct spi_gpio), GFP_KERNEL);
+ if (!spi_gpio) {
status = -ENOMEM;
goto gpio_free;
}
- spi_gpio = spi_master_get_devdata(master);
+
+ master = spi_alloc_master_bitbang(&pdev->dev, &spi_gpio->bitbang);
+ if (!master) {
+ status = -ENOMEM;
+ goto spi_gpio_free;
+ }
platform_set_drvdata(pdev, spi_gpio);

spi_gpio->pdev = pdev;
@@ -367,6 +372,8 @@ static int __init spi_gpio_probe(struct platform_device *pdev)
status = spi_bitbang_start(&spi_gpio->bitbang);
if (status < 0) {
spi_master_put(spi_gpio->bitbang.master);
+spi_gpio_free:
+ kfree(spi_gpio);
gpio_free:
if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO)
gpio_free(SPI_MISO_GPIO);
@@ -391,6 +398,7 @@ static int __exit spi_gpio_remove(struct platform_device *pdev)
/* stop() unregisters child devices too */
status = spi_bitbang_stop(&spi_gpio->bitbang);
spi_master_put(spi_gpio->bitbang.master);
+ kfree(spi_gpio);

platform_set_drvdata(pdev, NULL);

diff --git a/include/linux/spi/spi.h b/include/linux/spi/spi.h
index b4d7710..3f72a34 100644
--- a/include/linux/spi/spi.h
+++ b/include/linux/spi/spi.h
@@ -336,7 +336,8 @@ static inline void spi_master_put(struct spi_master *master)
/* the spi driver core manages memory for the spi_master classdev */
extern struct spi_master *
spi_alloc_master(struct device *host, unsigned size);
-
+extern struct spi_master *
+spi_alloc_master_bitbang(struct device *host, struct spi_bitbang *bitbang);
extern int spi_register_master(struct spi_master *master);
extern void spi_unregister_master(struct spi_master *master);

2011-02-16 02:47:51

by Grant Likely

[permalink] [raw]

Subject: Re: [PATCH v9] spi: New driver for Altera SPI

On Mon, Feb 14, 2011 at 10:10:43AM +0800, Thomas Chou 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 <[email protected]>

Applied, thanks.

g.

> ---
> v2 add devicetree support
> v3 remove platform header, as Grant suggested.
> no irq resource means polling.
> v4 minor cleanup, as Grant suggested.
> v5 add compat version.
> v6 change compatible vendor to uppercase, ALTR.
> add dts binding doc.
> v7 use platform driver register.
> use devm_ to help cleanup.
> v8 remove default n in Kconfig.
> v9 condition module device table export for of.
>
> .../devicetree/bindings/spi/spi_altera.txt | 4 +
> drivers/spi/Kconfig | 6 +
> drivers/spi/Makefile | 1 +
> drivers/spi/spi_altera.c | 339 ++++++++++++++++++++
> 4 files changed, 350 insertions(+), 0 deletions(-)
> create mode 100644 Documentation/devicetree/bindings/spi/spi_altera.txt
> create mode 100644 drivers/spi/spi_altera.c
>
> diff --git a/Documentation/devicetree/bindings/spi/spi_altera.txt b/Documentation/devicetree/bindings/spi/spi_altera.txt
> new file mode 100644
> index 0000000..dda3759
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/spi/spi_altera.txt
> @@ -0,0 +1,4 @@
> +Altera SPI
> +
> +Required properties:
> +- compatible : should be "ALTR,spi-1.0".
> diff --git a/drivers/spi/Kconfig b/drivers/spi/Kconfig
> index bb233a9..e791579 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_ATH79
> tristate "Atheros AR71XX/AR724X/AR913X SPI controller driver"
> depends on ATH79 && GENERIC_GPIO
> diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
> index 86d1b5f..4d2e35a 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-$(CONFIG_SPI_ATH79) += ath79_spi.o
> obj-$(CONFIG_SPI_BFIN) += spi_bfin5xx.o
> diff --git a/drivers/spi/spi_altera.c b/drivers/spi/spi_altera.c
> new file mode 100644
> index 0000000..5e001f3
> --- /dev/null
> +++ b/drivers/spi/spi_altera.c
> @@ -0,0 +1,339 @@
> +/*
> + * Altera SPI driver
> + *
> + * Copyright (C) 2008 Thomas Chou <[email protected]>
> + *
> + * Based on spi_s3c24xx.c, which is:
> + * Copyright (c) 2006 Ben Dooks
> + * Copyright (c) 2006 Simtec Electronics
> + * Ben Dooks <[email protected]>
> + *
> + * 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/interrupt.h>
> +#include <linux/errno.h>
> +#include <linux/platform_device.h>
> +#include <linux/spi/spi.h>
> +#include <linux/spi/spi_bitbang.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 len;
> + int count;
> + int bytes_per_word;
> + unsigned long imr;
> +
> + /* data buffers */
> + const unsigned char *tx;
> + unsigned char *rx;
> +};
> +
> +static inline struct altera_spi *altera_spi_to_hw(struct spi_device *sdev)
> +{
> + return spi_master_get_devdata(sdev->master);
> +}
> +
> +static void altera_spi_chipsel(struct spi_device *spi, int value)
> +{
> + struct altera_spi *hw = altera_spi_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 = altera_spi_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) {
> + /* 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;
> +}
> +
> +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 = -ENODEV;
> +
> + master = spi_alloc_master(&pdev->dev, sizeof(struct altera_spi));
> + if (!master)
> + return err;
> +
> + /* 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)
> + return err;
> + 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)
> + goto exit_busy;
> + if (!devm_request_mem_region(&pdev->dev, res->start, resource_size(res),
> + pdev->name))
> + goto exit_busy;
> + hw->base = devm_ioremap_nocache(&pdev->dev, res->start,
> + resource_size(res));
> + if (!hw->base)
> + goto exit_busy;
> + /* 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 = devm_request_irq(&pdev->dev, hw->irq, altera_spi_irq, 0,
> + pdev->name, hw);
> + if (err)
> + goto exit;
> + }
> + /* find platform data */
> + if (!platp)
> + hw->bitbang.master->dev.of_node = pdev->dev.of_node;
> +
> + /* register our spi controller */
> + err = spi_bitbang_start(&hw->bitbang);
> + if (err)
> + goto exit;
> + dev_info(&pdev->dev, "base %p, irq %d\n", hw->base, hw->irq);
> +
> + return 0;
> +
> +exit_busy:
> + err = -EBUSY;
> +exit:
> + platform_set_drvdata(pdev, NULL);
> + spi_master_put(master);
> + 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);
> + platform_set_drvdata(dev, NULL);
> + spi_master_put(master);
> + return 0;
> +}
> +
> +#ifdef CONFIG_OF
> +static const struct of_device_id altera_spi_match[] = {
> + { .compatible = "ALTR,spi-1.0", },
> + {},
> +}
> +MODULE_DEVICE_TABLE(of, altera_spi_match);
> +#else /* CONFIG_OF */
> +#define altera_spi_match NULL
> +#endif /* CONFIG_OF */
> +
> +static struct platform_driver altera_spi_driver = {
> + .probe = altera_spi_probe,
> + .remove = __devexit_p(altera_spi_remove),
> + .driver = {
> + .name = DRV_NAME,
> + .owner = THIS_MODULE,
> + .pm = NULL,
> + .of_match_table = altera_spi_match,
> + },
> +};
> +
> +static int __init altera_spi_init(void)
> +{
> + return platform_driver_register(&altera_spi_driver);
> +}
> +module_init(altera_spi_init);
> +
> +static void __exit altera_spi_exit(void)
> +{
> + platform_driver_unregister(&altera_spi_driver);
> +}
> +module_exit(altera_spi_exit);
> +
> +MODULE_DESCRIPTION("Altera SPI driver");
> +MODULE_AUTHOR("Thomas Chou <[email protected]>");
> +MODULE_LICENSE("GPL");
> +MODULE_ALIAS("platform:" DRV_NAME);
> --
> 1.7.4
>