spi: Add SPI GPIO bitbang driver
This adds a driver for SPI master by GPIO pins. Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
This commit is contained in:
Sebastian Hesselbarth
Sascha Hauer
parent
e1eb436242
commit
301765846b
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@ -18,6 +18,10 @@ config DRIVER_SPI_ATMEL
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bool "Atmel (AT91) SPI Master driver"
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depends on ARCH_AT91
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config DRIVER_SPI_GPIO
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bool "GPIO SPI Master driver"
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depends on GPIOLIB
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config DRIVER_SPI_IMX
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bool "i.MX SPI Master driver"
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depends on ARCH_IMX
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@ -1,5 +1,6 @@
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obj-$(CONFIG_SPI) += spi.o
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obj-$(CONFIG_DRIVER_SPI_ATH79) += ath79_spi.o
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obj-$(CONFIG_DRIVER_SPI_GPIO) += gpio_spi.o
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obj-$(CONFIG_DRIVER_SPI_IMX) += imx_spi.o
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obj-$(CONFIG_DRIVER_SPI_MVEBU) += mvebu_spi.o
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obj-$(CONFIG_DRIVER_SPI_MXS) += mxs_spi.o
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@ -0,0 +1,240 @@
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/*
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* SPI master driver using generic bitbanged GPIO
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*
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* Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
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*
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* Based on Linux driver
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* Copyright (C) 2006,2008 David Brownell
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#include <common.h>
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#include <driver.h>
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#include <errno.h>
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#include <gpio.h>
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#include <init.h>
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#include <io.h>
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#include <malloc.h>
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#include <of_gpio.h>
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#include <spi/spi.h>
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#include <spi/spi_gpio.h>
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struct gpio_spi {
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struct spi_master master;
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struct gpio_spi_pdata *data;
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};
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#define priv_from_spi_device(s) container_of(s->master, struct gpio_spi, master)
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static inline void setsck(const struct spi_device *spi, int is_on)
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{
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struct gpio_spi *priv = priv_from_spi_device(spi);
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gpio_set_value(priv->data->sck, is_on);
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}
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static inline void setmosi(const struct spi_device *spi, int is_on)
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{
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struct gpio_spi *priv = priv_from_spi_device(spi);
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if (!gpio_is_valid(priv->data->mosi))
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return;
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gpio_set_value(priv->data->mosi, is_on);
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}
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static inline int getmiso(const struct spi_device *spi)
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{
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struct gpio_spi *priv = priv_from_spi_device(spi);
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if (!gpio_is_valid(priv->data->miso))
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return 1;
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return !!gpio_get_value(priv->data->miso);
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}
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#define spidelay(nsecs) do { } while (0)
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#include "spi-bitbang-txrx.h"
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static int gpio_spi_set_cs(struct spi_device *spi, bool en)
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{
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struct gpio_spi *priv = priv_from_spi_device(spi);
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if (!gpio_is_valid(priv->data->cs[spi->chip_select]))
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return 0;
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gpio_set_value(priv->data->cs[spi->chip_select],
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(spi->mode & SPI_CS_HIGH) ? en : !en);
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return 0;
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}
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static inline u32 gpio_spi_txrx_word(struct spi_device *spi, unsigned nsecs,
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u32 word, u8 bits)
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{
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int cpol = !!(spi->mode & SPI_CPOL);
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if (spi->mode & SPI_CPHA)
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return bitbang_txrx_be_cpha1(spi, nsecs, cpol, word, bits);
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else
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return bitbang_txrx_be_cpha0(spi, nsecs, cpol, word, bits);
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}
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static int gpio_spi_transfer_one(struct spi_device *spi, struct spi_transfer *t)
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{
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bool read = (t->rx_buf) ? true : false;
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u32 word = 0;
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int n;
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for (n = 0; n < t->len; n++) {
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if (!read)
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word = ((const u8 *)t->tx_buf)[n];
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word = gpio_spi_txrx_word(spi, 0, word, 8);
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if (read)
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((u8 *)t->rx_buf)[n] = word & 0xff;
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}
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return 0;
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}
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static int gpio_spi_transfer(struct spi_device *spi, struct spi_message *msg)
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{
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struct spi_transfer *t;
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int ret;
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ret = gpio_spi_set_cs(spi, true);
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if (ret)
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return ret;
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list_for_each_entry(t, &msg->transfers, transfer_list) {
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ret = gpio_spi_transfer_one(spi, t);
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if (ret)
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return ret;
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msg->actual_length += t->len;
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}
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ret = gpio_spi_set_cs(spi, false);
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if (ret)
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return ret;
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return 0;
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}
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static int gpio_spi_setup(struct spi_device *spi)
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{
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if (spi->bits_per_word != 8) {
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dev_err(spi->master->dev, "master does not support %d bits per word\n",
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spi->bits_per_word);
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return -EINVAL;
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}
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return 0;
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}
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static int gpio_spi_of_probe(struct device_d *dev)
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{
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struct device_node *np = dev->device_node;
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struct gpio_spi_pdata *pdata;
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int n, sck;
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if (!IS_ENABLED(CONFIG_OFDEVICE) || dev->platform_data)
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return 0;
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sck = of_get_named_gpio(np, "gpio-sck", 0);
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if (sck == -EPROBE_DEFER)
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return sck;
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if (!gpio_is_valid(sck)) {
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dev_err(dev, "missing mandatory SCK gpio\n");
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return sck;
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}
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pdata = xzalloc(sizeof(*pdata));
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pdata->sck = sck;
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pdata->num_cs = MAX_CHIPSELECT;
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pdata->miso = of_get_named_gpio(np, "gpio-miso", 0);
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if (!gpio_is_valid(pdata->miso))
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pdata->miso = SPI_GPIO_NO_MISO;
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pdata->mosi = of_get_named_gpio(np, "gpio-mosi", 0);
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if (!gpio_is_valid(pdata->mosi))
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pdata->mosi = SPI_GPIO_NO_MOSI;
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for (n = 0; n < MAX_CHIPSELECT; n++) {
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pdata->cs[n] = of_get_named_gpio(np, "cs-gpios", n);
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if (!gpio_is_valid(pdata->cs[n]))
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pdata->cs[n] = SPI_GPIO_NO_CS;
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}
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dev->platform_data = pdata;
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return 0;
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}
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static int gpio_spi_probe(struct device_d *dev)
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{
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struct gpio_spi *priv;
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struct gpio_spi_pdata *pdata;
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struct spi_master *master;
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int n, ret;
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ret = gpio_spi_of_probe(dev);
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if (ret)
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return ret;
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pdata = dev->platform_data;
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ret = gpio_request_one(pdata->sck, GPIOF_DIR_OUT, "spi-sck");
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if (ret)
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return ret;
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if (pdata->miso != SPI_GPIO_NO_MISO) {
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ret = gpio_request_one(pdata->miso, GPIOF_DIR_IN, "spi-miso");
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if (ret)
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return ret;
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}
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if (pdata->mosi != SPI_GPIO_NO_MOSI) {
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ret = gpio_request_one(pdata->mosi, GPIOF_DIR_OUT, "spi-mosi");
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if (ret)
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return ret;
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}
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for (n = 0; n < pdata->num_cs; n++) {
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char *cs_name;
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if (!gpio_is_valid(pdata->cs[n]))
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continue;
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cs_name = asprintf("spi-cs%d", n);
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ret = gpio_request_one(pdata->cs[n], GPIOF_DIR_OUT, cs_name);
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if (ret)
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return ret;
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}
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priv = xzalloc(sizeof(*priv));
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priv->data = pdata;
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master = &priv->master;
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master->dev = dev;
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master->bus_num = dev->id;
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master->setup = gpio_spi_setup;
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master->transfer = gpio_spi_transfer;
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master->num_chipselect = priv->data->num_cs;
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return spi_register_master(&priv->master);
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}
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static struct of_device_id __maybe_unused gpio_spi_dt_ids[] = {
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{ .compatible = "spi-gpio", },
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{ }
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};
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static struct driver_d gpio_spi_driver = {
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.name = "gpio-spi",
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.probe = gpio_spi_probe,
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.of_compatible = DRV_OF_COMPAT(gpio_spi_dt_ids),
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};
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device_platform_driver(gpio_spi_driver);
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@ -0,0 +1,36 @@
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/*
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* SPI master driver using generic bitbanged GPIO
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*
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* Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
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*
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* Based on Linux driver
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* Copyright (C) 2006,2008 David Brownell
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#ifndef __SPI_GPIO_H
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#define __SPI_GPIO_H
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#define MAX_CHIPSELECT 4
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#define SPI_GPIO_NO_CS (-1)
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#define SPI_GPIO_NO_MISO (-1)
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#define SPI_GPIO_NO_MOSI (-1)
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struct gpio_spi_pdata {
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int sck;
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int mosi;
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int miso;
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int cs[MAX_CHIPSELECT];
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int num_cs;
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};
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#endif
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