diff options
Diffstat (limited to 'drivers/spi/spi_gpio.c')
| -rw-r--r-- | drivers/spi/spi_gpio.c | 429 |
1 files changed, 0 insertions, 429 deletions
diff --git a/drivers/spi/spi_gpio.c b/drivers/spi/spi_gpio.c deleted file mode 100644 index 63e51b011d5..00000000000 --- a/drivers/spi/spi_gpio.c +++ /dev/null @@ -1,429 +0,0 @@ -/* - * spi_gpio.c - SPI master driver using generic bitbanged GPIO - * - * Copyright (C) 2006,2008 David Brownell - * - * 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., 675 Mass Ave, Cambridge, MA 02139, USA. - */ -#include <linux/kernel.h> -#include <linux/init.h> -#include <linux/platform_device.h> -#include <linux/gpio.h> - -#include <linux/spi/spi.h> -#include <linux/spi/spi_bitbang.h> -#include <linux/spi/spi_gpio.h> - - -/* - * This bitbanging SPI master driver should help make systems usable - * when a native hardware SPI engine is not available, perhaps because - * its driver isn't yet working or because the I/O pins it requires - * are used for other purposes. - * - * platform_device->driver_data ... points to spi_gpio - * - * spi->controller_state ... reserved for bitbang framework code - * spi->controller_data ... holds chipselect GPIO - * - * spi->master->dev.driver_data ... points to spi_gpio->bitbang - */ - -struct spi_gpio { - struct spi_bitbang bitbang; - struct spi_gpio_platform_data pdata; - struct platform_device *pdev; -}; - -/*----------------------------------------------------------------------*/ - -/* - * Because the overhead of going through four GPIO procedure calls - * per transferred bit can make performance a problem, this code - * is set up so that you can use it in either of two ways: - * - * - The slow generic way: set up platform_data to hold the GPIO - * numbers used for MISO/MOSI/SCK, and issue procedure calls for - * each of them. This driver can handle several such busses. - * - * - The quicker inlined way: only helps with platform GPIO code - * that inlines operations for constant GPIOs. This can give - * you tight (fast!) inner loops, but each such bus needs a - * new driver. You'll define a new C file, with Makefile and - * Kconfig support; the C code can be a total of six lines: - * - * #define DRIVER_NAME "myboard_spi2" - * #define SPI_MISO_GPIO 119 - * #define SPI_MOSI_GPIO 120 - * #define SPI_SCK_GPIO 121 - * #define SPI_N_CHIPSEL 4 - * #include "spi_gpio.c" - */ - -#ifndef DRIVER_NAME -#define DRIVER_NAME "spi_gpio" - -#define GENERIC_BITBANG /* vs tight inlines */ - -/* all functions referencing these symbols must define pdata */ -#define SPI_MISO_GPIO ((pdata)->miso) -#define SPI_MOSI_GPIO ((pdata)->mosi) -#define SPI_SCK_GPIO ((pdata)->sck) - -#define SPI_N_CHIPSEL ((pdata)->num_chipselect) - -#endif - -/*----------------------------------------------------------------------*/ - -static inline const struct spi_gpio_platform_data * __pure -spi_to_pdata(const struct spi_device *spi) -{ - const struct spi_bitbang *bang; - const struct spi_gpio *spi_gpio; - - bang = spi_master_get_devdata(spi->master); - spi_gpio = container_of(bang, struct spi_gpio, bitbang); - return &spi_gpio->pdata; -} - -/* this is #defined to avoid unused-variable warnings when inlining */ -#define pdata spi_to_pdata(spi) - -static inline void setsck(const struct spi_device *spi, int is_on) -{ - gpio_set_value(SPI_SCK_GPIO, is_on); -} - -static inline void setmosi(const struct spi_device *spi, int is_on) -{ - gpio_set_value(SPI_MOSI_GPIO, is_on); -} - -static inline int getmiso(const struct spi_device *spi) -{ - return !!gpio_get_value(SPI_MISO_GPIO); -} - -#undef pdata - -/* - * NOTE: this clocks "as fast as we can". It "should" be a function of the - * requested device clock. Software overhead means we usually have trouble - * reaching even one Mbit/sec (except when we can inline bitops), so for now - * we'll just assume we never need additional per-bit slowdowns. - */ -#define spidelay(nsecs) do {} while (0) - -#include "spi_bitbang_txrx.h" - -/* - * These functions can leverage inline expansion of GPIO calls to shrink - * costs for a txrx bit, often by factors of around ten (by instruction - * count). That is particularly visible for larger word sizes, but helps - * even with default 8-bit words. - * - * REVISIT overheads calling these functions for each word also have - * significant performance costs. Having txrx_bufs() calls that inline - * the txrx_word() logic would help performance, e.g. on larger blocks - * used with flash storage or MMC/SD. There should also be ways to make - * GCC be less stupid about reloading registers inside the I/O loops, - * even without inlined GPIO calls; __attribute__((hot)) on GCC 4.3? - */ - -static u32 spi_gpio_txrx_word_mode0(struct spi_device *spi, - unsigned nsecs, u32 word, u8 bits) -{ - return bitbang_txrx_be_cpha0(spi, nsecs, 0, 0, word, bits); -} - -static u32 spi_gpio_txrx_word_mode1(struct spi_device *spi, - unsigned nsecs, u32 word, u8 bits) -{ - return bitbang_txrx_be_cpha1(spi, nsecs, 0, 0, word, bits); -} - -static u32 spi_gpio_txrx_word_mode2(struct spi_device *spi, - unsigned nsecs, u32 word, u8 bits) -{ - return bitbang_txrx_be_cpha0(spi, nsecs, 1, 0, word, bits); -} - -static u32 spi_gpio_txrx_word_mode3(struct spi_device *spi, - unsigned nsecs, u32 word, u8 bits) -{ - return bitbang_txrx_be_cpha1(spi, nsecs, 1, 0, word, bits); -} - -/* - * These functions do not call setmosi or getmiso if respective flag - * (SPI_MASTER_NO_RX or SPI_MASTER_NO_TX) is set, so they are safe to - * call when such pin is not present or defined in the controller. - * A separate set of callbacks is defined to get highest possible - * speed in the generic case (when both MISO and MOSI lines are - * available), as optimiser will remove the checks when argument is - * constant. - */ - -static u32 spi_gpio_spec_txrx_word_mode0(struct spi_device *spi, - unsigned nsecs, u32 word, u8 bits) -{ - unsigned flags = spi->master->flags; - return bitbang_txrx_be_cpha0(spi, nsecs, 0, flags, word, bits); -} - -static u32 spi_gpio_spec_txrx_word_mode1(struct spi_device *spi, - unsigned nsecs, u32 word, u8 bits) -{ - unsigned flags = spi->master->flags; - return bitbang_txrx_be_cpha1(spi, nsecs, 0, flags, word, bits); -} - -static u32 spi_gpio_spec_txrx_word_mode2(struct spi_device *spi, - unsigned nsecs, u32 word, u8 bits) -{ - unsigned flags = spi->master->flags; - return bitbang_txrx_be_cpha0(spi, nsecs, 1, flags, word, bits); -} - -static u32 spi_gpio_spec_txrx_word_mode3(struct spi_device *spi, - unsigned nsecs, u32 word, u8 bits) -{ - unsigned flags = spi->master->flags; - return bitbang_txrx_be_cpha1(spi, nsecs, 1, flags, word, bits); -} - -/*----------------------------------------------------------------------*/ - -static void spi_gpio_chipselect(struct spi_device *spi, int is_active) -{ - unsigned long cs = (unsigned long) spi->controller_data; - - /* set initial clock polarity */ - if (is_active) - setsck(spi, spi->mode & SPI_CPOL); - - if (cs != SPI_GPIO_NO_CHIPSELECT) { - /* SPI is normally active-low */ - gpio_set_value(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active); - } -} - -static int spi_gpio_setup(struct spi_device *spi) -{ - unsigned long cs = (unsigned long) spi->controller_data; - int status = 0; - - if (spi->bits_per_word > 32) - return -EINVAL; - - if (!spi->controller_state) { - if (cs != SPI_GPIO_NO_CHIPSELECT) { - status = gpio_request(cs, dev_name(&spi->dev)); - if (status) - return status; - status = gpio_direction_output(cs, spi->mode & SPI_CS_HIGH); - } - } - if (!status) - status = spi_bitbang_setup(spi); - if (status) { - if (!spi->controller_state && cs != SPI_GPIO_NO_CHIPSELECT) - gpio_free(cs); - } - return status; -} - -static void spi_gpio_cleanup(struct spi_device *spi) -{ - unsigned long cs = (unsigned long) spi->controller_data; - - if (cs != SPI_GPIO_NO_CHIPSELECT) - gpio_free(cs); - spi_bitbang_cleanup(spi); -} - -static int __init spi_gpio_alloc(unsigned pin, const char *label, bool is_in) -{ - int value; - - value = gpio_request(pin, label); - if (value == 0) { - if (is_in) - value = gpio_direction_input(pin); - else - value = gpio_direction_output(pin, 0); - } - return value; -} - -static int __init -spi_gpio_request(struct spi_gpio_platform_data *pdata, const char *label, - u16 *res_flags) -{ - int value; - - /* NOTE: SPI_*_GPIO symbols may reference "pdata" */ - - if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI) { - value = spi_gpio_alloc(SPI_MOSI_GPIO, label, false); - if (value) - goto done; - } else { - /* HW configuration without MOSI pin */ - *res_flags |= SPI_MASTER_NO_TX; - } - - if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO) { - value = spi_gpio_alloc(SPI_MISO_GPIO, label, true); - if (value) - goto free_mosi; - } else { - /* HW configuration without MISO pin */ - *res_flags |= SPI_MASTER_NO_RX; - } - - value = spi_gpio_alloc(SPI_SCK_GPIO, label, false); - if (value) - goto free_miso; - - goto done; - -free_miso: - if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO) - gpio_free(SPI_MISO_GPIO); -free_mosi: - if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI) - gpio_free(SPI_MOSI_GPIO); -done: - return value; -} - -static int __init spi_gpio_probe(struct platform_device *pdev) -{ - int status; - struct spi_master *master; - struct spi_gpio *spi_gpio; - struct spi_gpio_platform_data *pdata; - u16 master_flags = 0; - - pdata = pdev->dev.platform_data; -#ifdef GENERIC_BITBANG - if (!pdata || !pdata->num_chipselect) - return -ENODEV; -#endif - - status = spi_gpio_request(pdata, dev_name(&pdev->dev), &master_flags); - if (status < 0) - return status; - - master = spi_alloc_master(&pdev->dev, sizeof *spi_gpio); - if (!master) { - status = -ENOMEM; - goto gpio_free; - } - spi_gpio = spi_master_get_devdata(master); - platform_set_drvdata(pdev, spi_gpio); - - spi_gpio->pdev = pdev; - if (pdata) - spi_gpio->pdata = *pdata; - - master->flags = master_flags; - master->bus_num = pdev->id; - master->num_chipselect = SPI_N_CHIPSEL; - master->setup = spi_gpio_setup; - master->cleanup = spi_gpio_cleanup; - - spi_gpio->bitbang.master = spi_master_get(master); - spi_gpio->bitbang.chipselect = spi_gpio_chipselect; - - if ((master_flags & (SPI_MASTER_NO_TX | SPI_MASTER_NO_RX)) == 0) { - spi_gpio->bitbang.txrx_word[SPI_MODE_0] = spi_gpio_txrx_word_mode0; - spi_gpio->bitbang.txrx_word[SPI_MODE_1] = spi_gpio_txrx_word_mode1; - spi_gpio->bitbang.txrx_word[SPI_MODE_2] = spi_gpio_txrx_word_mode2; - spi_gpio->bitbang.txrx_word[SPI_MODE_3] = spi_gpio_txrx_word_mode3; - } else { - spi_gpio->bitbang.txrx_word[SPI_MODE_0] = spi_gpio_spec_txrx_word_mode0; - spi_gpio->bitbang.txrx_word[SPI_MODE_1] = spi_gpio_spec_txrx_word_mode1; - spi_gpio->bitbang.txrx_word[SPI_MODE_2] = spi_gpio_spec_txrx_word_mode2; - spi_gpio->bitbang.txrx_word[SPI_MODE_3] = spi_gpio_spec_txrx_word_mode3; - } - spi_gpio->bitbang.setup_transfer = spi_bitbang_setup_transfer; - spi_gpio->bitbang.flags = SPI_CS_HIGH; - - status = spi_bitbang_start(&spi_gpio->bitbang); - if (status < 0) { - spi_master_put(spi_gpio->bitbang.master); -gpio_free: - if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO) - gpio_free(SPI_MISO_GPIO); - if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI) - gpio_free(SPI_MOSI_GPIO); - gpio_free(SPI_SCK_GPIO); - spi_master_put(master); - } - - return status; -} - -static int __exit spi_gpio_remove(struct platform_device *pdev) -{ - struct spi_gpio *spi_gpio; - struct spi_gpio_platform_data *pdata; - int status; - - spi_gpio = platform_get_drvdata(pdev); - pdata = pdev->dev.platform_data; - - /* stop() unregisters child devices too */ - status = spi_bitbang_stop(&spi_gpio->bitbang); - spi_master_put(spi_gpio->bitbang.master); - - platform_set_drvdata(pdev, NULL); - - if (SPI_MISO_GPIO != SPI_GPIO_NO_MISO) - gpio_free(SPI_MISO_GPIO); - if (SPI_MOSI_GPIO != SPI_GPIO_NO_MOSI) - gpio_free(SPI_MOSI_GPIO); - gpio_free(SPI_SCK_GPIO); - - return status; -} - -MODULE_ALIAS("platform:" DRIVER_NAME); - -static struct platform_driver spi_gpio_driver = { - .driver.name = DRIVER_NAME, - .driver.owner = THIS_MODULE, - .remove = __exit_p(spi_gpio_remove), -}; - -static int __init spi_gpio_init(void) -{ - return platform_driver_probe(&spi_gpio_driver, spi_gpio_probe); -} -module_init(spi_gpio_init); - -static void __exit spi_gpio_exit(void) -{ - platform_driver_unregister(&spi_gpio_driver); -} -module_exit(spi_gpio_exit); - - -MODULE_DESCRIPTION("SPI master driver using generic bitbanged GPIO "); -MODULE_AUTHOR("David Brownell"); -MODULE_LICENSE("GPL"); |