cregit-Linux how code gets into the kernel

Release 4.14 drivers/spi/spi-gpio.c

Directory: drivers/spi
/*
 * 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.
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/gpio.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/of_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;
	
unsigned long			cs_gpios[0];
};

/*----------------------------------------------------------------------*/

/*
 * 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 struct spi_gpio *__pure spi_to_spi_gpio(const struct spi_device *spi) { const struct spi_bitbang *bang; struct spi_gpio *spi_gpio; bang = spi_master_get_devdata(spi->master); spi_gpio = container_of(bang, struct spi_gpio, bitbang); return spi_gpio; }

Contributors

PersonTokensPropCommitsCommitProp
David Brownell4792.16%150.00%
Daniel Mack47.84%150.00%
Total51100.00%2100.00%


static inline struct spi_gpio_platform_data *__pure spi_to_pdata(const struct spi_device *spi) { return &spi_to_spi_gpio(spi)->pdata; }

Contributors

PersonTokensPropCommitsCommitProp
Daniel Mack2184.00%150.00%
David Brownell416.00%150.00%
Total25100.00%2100.00%

/* 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_cansleep(SPI_SCK_GPIO, is_on); }

Contributors

PersonTokensPropCommitsCommitProp
David Brownell2295.65%150.00%
Ezequiel García14.35%150.00%
Total23100.00%2100.00%


static inline void setmosi(const struct spi_device *spi, int is_on) { gpio_set_value_cansleep(SPI_MOSI_GPIO, is_on); }

Contributors

PersonTokensPropCommitsCommitProp
David Brownell2295.65%150.00%
Ezequiel García14.35%150.00%
Total23100.00%2100.00%


static inline int getmiso(const struct spi_device *spi) { return !!gpio_get_value_cansleep(SPI_MISO_GPIO); }

Contributors

PersonTokensPropCommitsCommitProp
David Brownell1885.71%133.33%
Michael Büsch29.52%133.33%
Ezequiel García14.76%133.33%
Total21100.00%3100.00%

#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); }

Contributors

PersonTokensPropCommitsCommitProp
David Brownell3494.44%150.00%
Marek Szyprowski25.56%150.00%
Total36100.00%2100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
David Brownell3494.44%150.00%
Marek Szyprowski25.56%150.00%
Total36100.00%2100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
David Brownell3494.44%150.00%
Marek Szyprowski25.56%150.00%
Total36100.00%2100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
David Brownell3494.44%150.00%
Marek Szyprowski25.56%150.00%
Total36100.00%2100.00%

/* * 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); }

Contributors

PersonTokensPropCommitsCommitProp
Marek Szyprowski45100.00%1100.00%
Total45100.00%1100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
Marek Szyprowski45100.00%1100.00%
Total45100.00%1100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
Marek Szyprowski45100.00%1100.00%
Total45100.00%1100.00%


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); }

Contributors

PersonTokensPropCommitsCommitProp
Marek Szyprowski45100.00%1100.00%
Total45100.00%1100.00%

/*----------------------------------------------------------------------*/
static void spi_gpio_chipselect(struct spi_device *spi, int is_active) { struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi); unsigned long cs = spi_gpio->cs_gpios[spi->chip_select]; /* 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_cansleep(cs, (spi->mode & SPI_CS_HIGH) ? is_active : !is_active); } }

Contributors

PersonTokensPropCommitsCommitProp
David Brownell5467.50%120.00%
Daniel Mack1620.00%120.00%
Michael Büsch810.00%120.00%
Torsten Fleischer11.25%120.00%
Ezequiel García11.25%120.00%
Total80100.00%5100.00%


static int spi_gpio_setup(struct spi_device *spi) { unsigned long cs; int status = 0; struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi); struct device_node *np = spi->master->dev.of_node; if (np) { /* * In DT environments, the CS GPIOs have already been * initialized from the "cs-gpios" property of the node. */ cs = spi_gpio->cs_gpios[spi->chip_select]; } else { /* * ... otherwise, take it from spi->controller_data */ cs = (uintptr_t) spi->controller_data; } 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) { /* in case it was initialized from static board data */ spi_gpio->cs_gpios[spi->chip_select] = cs; status = spi_bitbang_setup(spi); } if (status) { if (!spi->controller_state && cs != SPI_GPIO_NO_CHIPSELECT) gpio_free(cs); } return status; }

Contributors

PersonTokensPropCommitsCommitProp
David Brownell8547.22%111.11%
Daniel Mack6636.67%222.22%
Michael Büsch126.67%111.11%
Josef Ahmad73.89%111.11%
Kay Sievers42.22%111.11%
Uwe Kleine-König31.67%111.11%
SeongJae Park21.11%111.11%
Torsten Fleischer10.56%111.11%
Total180100.00%9100.00%


static void spi_gpio_cleanup(struct spi_device *spi) { struct spi_gpio *spi_gpio = spi_to_spi_gpio(spi); unsigned long cs = spi_gpio->cs_gpios[spi->chip_select]; if (cs != SPI_GPIO_NO_CHIPSELECT) gpio_free(cs); spi_bitbang_cleanup(spi); }

Contributors

PersonTokensPropCommitsCommitProp
David Brownell2754.00%125.00%
Daniel Mack1632.00%125.00%
Michael Büsch612.00%125.00%
Torsten Fleischer12.00%125.00%
Total50100.00%4100.00%


static int 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; }

Contributors

PersonTokensPropCommitsCommitProp
David Brownell61100.00%1100.00%
Total61100.00%1100.00%


static int 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; }

Contributors

PersonTokensPropCommitsCommitProp
David Brownell9665.75%150.00%
Marek Szyprowski5034.25%150.00%
Total146100.00%2100.00%

#ifdef CONFIG_OF static const struct of_device_id spi_gpio_dt_ids[] = { { .compatible = "spi-gpio" }, {} }; MODULE_DEVICE_TABLE(of, spi_gpio_dt_ids);
static int spi_gpio_probe_dt(struct platform_device *pdev) { int ret; u32 tmp; struct spi_gpio_platform_data *pdata; struct device_node *np = pdev->dev.of_node; const struct of_device_id *of_id = of_match_device(spi_gpio_dt_ids, &pdev->dev); if (!of_id) return 0; pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL); if (!pdata) return -ENOMEM; ret = of_get_named_gpio(np, "gpio-sck", 0); if (ret < 0) { dev_err(&pdev->dev, "gpio-sck property not found\n"); goto error_free; } pdata->sck = ret; ret = of_get_named_gpio(np, "gpio-miso", 0); if (ret < 0) { dev_info(&pdev->dev, "gpio-miso property not found, switching to no-rx mode\n"); pdata->miso = SPI_GPIO_NO_MISO; } else pdata->miso = ret; ret = of_get_named_gpio(np, "gpio-mosi", 0); if (ret < 0) { dev_info(&pdev->dev, "gpio-mosi property not found, switching to no-tx mode\n"); pdata->mosi = SPI_GPIO_NO_MOSI; } else pdata->mosi = ret; ret = of_property_read_u32(np, "num-chipselects", &tmp); if (ret < 0) { dev_err(&pdev->dev, "num-chipselects property not found\n"); goto error_free; } pdata->num_chipselect = tmp; pdev->dev.platform_data = pdata; return 1; error_free: devm_kfree(&pdev->dev, pdata); return ret; }

Contributors

PersonTokensPropCommitsCommitProp
Daniel Mack18367.53%150.00%
Maxime Ripard8832.47%150.00%
Total271100.00%2100.00%

#else
static inline int spi_gpio_probe_dt(struct platform_device *pdev) { return 0; }

Contributors

PersonTokensPropCommitsCommitProp
Daniel Mack1386.67%150.00%
Mark Brown213.33%150.00%
Total15100.00%2100.00%

#endif
static int 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; bool use_of = 0; int num_devices; status = spi_gpio_probe_dt(pdev); if (status < 0) return status; if (status > 0) use_of = 1; pdata = dev_get_platdata(&pdev->dev); #ifdef GENERIC_BITBANG if (!pdata || (!use_of && !pdata->num_chipselect)) return -ENODEV; #endif if (use_of && !SPI_N_CHIPSEL) num_devices = 1; else num_devices = SPI_N_CHIPSEL; 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) + (sizeof(unsigned long) * num_devices)); 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->bits_per_word_mask = SPI_BPW_RANGE_MASK(1, 32); master->flags = master_flags; master->bus_num = pdev->id; master->num_chipselect = num_devices; master->setup = spi_gpio_setup; master->cleanup = spi_gpio_cleanup; #ifdef CONFIG_OF master->dev.of_node = pdev->dev.of_node; if (use_of) { int i; struct device_node *np = pdev->dev.of_node; /* * In DT environments, take the CS GPIO from the "cs-gpios" * property of the node. */ if (!SPI_N_CHIPSEL) spi_gpio->cs_gpios[0] = SPI_GPIO_NO_CHIPSELECT; else for (i = 0; i < SPI_N_CHIPSEL; i++) { status = of_get_named_gpio(np, "cs-gpios", i); if (status < 0) { dev_err(&pdev->dev, "invalid cs-gpios property\n"); goto gpio_free; } spi_gpio->cs_gpios[i] = status; } } #endif spi_gpio->bitbang.master = 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) { 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; }

Contributors

PersonTokensPropCommitsCommitProp
David Brownell28149.91%111.11%
Daniel Mack9917.58%222.22%
Marek Szyprowski8815.63%111.11%
Torsten Fleischer7914.03%222.22%
Stephen Warren111.95%111.11%
Jingoo Han40.71%111.11%
Roel Kluin10.18%111.11%
Total563100.00%9100.00%


static int spi_gpio_remove(struct platform_device *pdev) { struct spi_gpio *spi_gpio; struct spi_gpio_platform_data *pdata; spi_gpio = platform_get_drvdata(pdev); pdata = dev_get_platdata(&pdev->dev); /* stop() unregisters child devices too */ spi_bitbang_stop(&spi_gpio->bitbang); 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(spi_gpio->bitbang.master); return 0; }

Contributors

PersonTokensPropCommitsCommitProp
David Brownell6069.77%120.00%
Marek Szyprowski1213.95%120.00%
Axel Lin1011.63%240.00%
Jingoo Han44.65%120.00%
Total86100.00%5100.00%

MODULE_ALIAS("platform:" DRIVER_NAME); static struct platform_driver spi_gpio_driver = { .driver = { .name = DRIVER_NAME, .of_match_table = of_match_ptr(spi_gpio_dt_ids), }, .probe = spi_gpio_probe, .remove = spi_gpio_remove, }; module_platform_driver(spi_gpio_driver); MODULE_DESCRIPTION("SPI master driver using generic bitbanged GPIO "); MODULE_AUTHOR("David Brownell"); MODULE_LICENSE("GPL");

Overall Contributors

PersonTokensPropCommitsCommitProp
David Brownell104649.25%13.70%
Daniel Mack47122.18%27.41%
Marek Szyprowski33915.96%27.41%
Maxime Ripard884.14%13.70%
Torsten Fleischer843.95%27.41%
Michael Büsch281.32%27.41%
Stephen Warren110.52%13.70%
Axel Lin100.47%27.41%
Jingoo Han90.42%27.41%
Grant C. Likely80.38%27.41%
Josef Ahmad70.33%13.70%
Ezequiel García40.19%13.70%
Kay Sievers40.19%13.70%
Sachin Kamat30.14%13.70%
Paul Gortmaker30.14%13.70%
Uwe Kleine-König30.14%13.70%
Mark Brown20.09%13.70%
SeongJae Park20.09%13.70%
Roel Kluin10.05%13.70%
Jarkko Nikula10.05%13.70%
Total2124100.00%27100.00%
Directory: drivers/spi
Information contained on this website is for historical information purposes only and does not indicate or represent copyright ownership.
Created with cregit.