diff options
| -rw-r--r-- | doc/device-tree-bindings/spi/soft-spi.txt | 34 | ||||
| -rw-r--r-- | drivers/spi/Makefile | 1 | ||||
| -rw-r--r-- | drivers/spi/soft_spi.c | 252 |
3 files changed, 287 insertions, 0 deletions
diff --git a/doc/device-tree-bindings/spi/soft-spi.txt b/doc/device-tree-bindings/spi/soft-spi.txt new file mode 100644 index 0000000..d09c1a5 --- /dev/null +++ b/doc/device-tree-bindings/spi/soft-spi.txt @@ -0,0 +1,34 @@ +Soft SPI + +The soft SPI bus implementation allows the use of GPIO pins to simulate a +SPI bus. No SPI host is required for this to work. The down-side is that the +performance will typically be much lower than a real SPI bus. + +The soft SPI node requires the following properties: + +compatible: "u-boot,soft-spi" +soft_spi_cs: GPIO number to use for SPI chip select (output) +soft_spi_sclk: GPIO number to use for SPI clock (output) +soft_spi_mosi: GPIO number to use for SPI MOSI line (output) +soft_spi_miso GPIO number to use for SPI MISO line (input) +spi-delay-us: Number of microseconds of delay between each CS transition + +The GPIOs should be specified as required by the GPIO controller referenced. +The first cell holds the phandle of the controller and the second cell +typically holds the GPIO number. + + +Example: + + soft-spi { + compatible = "u-boot,soft-spi"; + cs-gpio = <&gpio 235 0>; /* Y43 */ + sclk-gpio = <&gpio 225 0>; /* Y31 */ + mosi-gpio = <&gpio 227 0>; /* Y33 */ + miso-gpio = <&gpio 224 0>; /* Y30 */ + spi-delay-us = <1>; + #address-cells = <1>; + #size-cells = <0>; + cs@0 { + }; + }; diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile index 5cc8655..e718528 100644 --- a/drivers/spi/Makefile +++ b/drivers/spi/Makefile @@ -9,6 +9,7 @@ ifdef CONFIG_DM_SPI obj-y += spi-uclass.o obj-$(CONFIG_SANDBOX) += spi-emul-uclass.o +obj-$(CONFIG_SOFT_SPI) += soft_spi.o else obj-y += spi.o obj-$(CONFIG_SOFT_SPI) += soft_spi_legacy.o diff --git a/drivers/spi/soft_spi.c b/drivers/spi/soft_spi.c new file mode 100644 index 0000000..5588036 --- /dev/null +++ b/drivers/spi/soft_spi.c @@ -0,0 +1,252 @@ +/* + * Copyright (c) 2014 Google, Inc + * + * (C) Copyright 2002 + * Gerald Van Baren, Custom IDEAS, vanbaren@cideas.com. + * + * Influenced by code from: + * Wolfgang Denk, DENX Software Engineering, wd@denx.de. + * + * SPDX-License-Identifier: GPL-2.0+ + */ + +#include <common.h> +#include <dm.h> +#include <errno.h> +#include <fdtdec.h> +#include <malloc.h> +#include <spi.h> +#include <asm/gpio.h> + +DECLARE_GLOBAL_DATA_PTR; + +struct soft_spi_platdata { + struct fdt_gpio_state cs; + struct fdt_gpio_state sclk; + struct fdt_gpio_state mosi; + struct fdt_gpio_state miso; + int spi_delay_us; +}; + +struct soft_spi_priv { + unsigned int mode; +}; + +static int soft_spi_scl(struct udevice *dev, int bit) +{ + struct soft_spi_platdata *plat = dev->platdata; + struct soft_spi_priv *priv = dev_get_priv(dev); + + gpio_set_value(plat->sclk.gpio, priv->mode & SPI_CPOL ? bit : !bit); + + return 0; +} + +static int soft_spi_sda(struct udevice *dev, int bit) +{ + struct soft_spi_platdata *plat = dev->platdata; + + gpio_set_value(plat->mosi.gpio, bit); + + return 0; +} + +static int soft_spi_cs_activate(struct udevice *dev) +{ + struct soft_spi_platdata *plat = dev->platdata; + struct soft_spi_priv *priv = dev_get_priv(dev); + + gpio_set_value(plat->cs.gpio, !(priv->mode & SPI_CS_HIGH)); + gpio_set_value(plat->sclk.gpio, priv->mode & SPI_CPOL); + gpio_set_value(plat->cs.gpio, priv->mode & SPI_CS_HIGH); + + return 0; +} + +static int soft_spi_cs_deactivate(struct udevice *dev) +{ + struct soft_spi_platdata *plat = dev->platdata; + struct soft_spi_priv *priv = dev_get_priv(dev); + + gpio_set_value(plat->cs.gpio, !(priv->mode & SPI_CS_HIGH)); + + return 0; +} + +static int soft_spi_claim_bus(struct udevice *dev) +{ + /* + * Make sure the SPI clock is in idle state as defined for + * this slave. + */ + return soft_spi_scl(dev, 0); +} + +static int soft_spi_release_bus(struct udevice *dev) +{ + /* Nothing to do */ + return 0; +} + +/*----------------------------------------------------------------------- + * SPI transfer + * + * This writes "bitlen" bits out the SPI MOSI port and simultaneously clocks + * "bitlen" bits in the SPI MISO port. That's just the way SPI works. + * + * The source of the outgoing bits is the "dout" parameter and the + * destination of the input bits is the "din" parameter. Note that "dout" + * and "din" can point to the same memory location, in which case the + * input data overwrites the output data (since both are buffered by + * temporary variables, this is OK). + */ +static int soft_spi_xfer(struct udevice *dev, unsigned int bitlen, + const void *dout, void *din, unsigned long flags) +{ + struct soft_spi_priv *priv = dev_get_priv(dev); + struct soft_spi_platdata *plat = dev->platdata; + uchar tmpdin = 0; + uchar tmpdout = 0; + const u8 *txd = dout; + u8 *rxd = din; + int cpol = priv->mode & SPI_CPOL; + int cpha = priv->mode & SPI_CPHA; + unsigned int j; + + debug("spi_xfer: slave %s:%s dout %08X din %08X bitlen %u\n", + dev->parent->name, dev->name, *(uint *)txd, *(uint *)rxd, + bitlen); + + if (flags & SPI_XFER_BEGIN) + soft_spi_cs_activate(dev); + + for (j = 0; j < bitlen; j++) { + /* + * Check if it is time to work on a new byte. + */ + if ((j % 8) == 0) { + if (txd) + tmpdout = *txd++; + else + tmpdout = 0; + if (j != 0) { + if (rxd) + *rxd++ = tmpdin; + } + tmpdin = 0; + } + + if (!cpha) + soft_spi_scl(dev, !cpol); + soft_spi_sda(dev, tmpdout & 0x80); + udelay(plat->spi_delay_us); + if (cpha) + soft_spi_scl(dev, !cpol); + else + soft_spi_scl(dev, cpol); + tmpdin <<= 1; + tmpdin |= gpio_get_value(plat->miso.gpio); + tmpdout <<= 1; + udelay(plat->spi_delay_us); + if (cpha) + soft_spi_scl(dev, cpol); + } + /* + * If the number of bits isn't a multiple of 8, shift the last + * bits over to left-justify them. Then store the last byte + * read in. + */ + if (rxd) { + if ((bitlen % 8) != 0) + tmpdin <<= 8 - (bitlen % 8); + *rxd++ = tmpdin; + } + + if (flags & SPI_XFER_END) + soft_spi_cs_deactivate(dev); + + return 0; +} + +static int soft_spi_set_speed(struct udevice *dev, unsigned int speed) +{ + /* Accept any speed */ + return 0; +} + +static int soft_spi_set_mode(struct udevice *dev, unsigned int mode) +{ + struct soft_spi_priv *priv = dev_get_priv(dev); + + priv->mode = mode; + + return 0; +} + +static int soft_spi_child_pre_probe(struct udevice *dev) +{ + struct spi_slave *slave = dev_get_parentdata(dev); + + slave->dev = dev; + return spi_ofdata_to_platdata(gd->fdt_blob, dev->of_offset, slave); +} + +static const struct dm_spi_ops soft_spi_ops = { + .claim_bus = soft_spi_claim_bus, + .release_bus = soft_spi_release_bus, + .xfer = soft_spi_xfer, + .set_speed = soft_spi_set_speed, + .set_mode = soft_spi_set_mode, +}; + +static int soft_spi_ofdata_to_platdata(struct udevice *dev) +{ + struct soft_spi_platdata *plat = dev->platdata; + const void *blob = gd->fdt_blob; + int node = dev->of_offset; + + if (fdtdec_decode_gpio(blob, node, "cs-gpio", &plat->cs) || + fdtdec_decode_gpio(blob, node, "sclk-gpio", &plat->sclk) || + fdtdec_decode_gpio(blob, node, "mosi-gpio", &plat->mosi) || + fdtdec_decode_gpio(blob, node, "miso-gpio", &plat->miso)) + return -EINVAL; + plat->spi_delay_us = fdtdec_get_int(blob, node, "spi-delay-us", 0); + + return 0; +} + +static int soft_spi_probe(struct udevice *dev) +{ + struct spi_slave *slave = dev_get_parentdata(dev); + struct soft_spi_platdata *plat = dev->platdata; + + gpio_request(plat->cs.gpio, "soft_spi_cs"); + gpio_request(plat->sclk.gpio, "soft_spi_sclk"); + gpio_request(plat->mosi.gpio, "soft_spi_mosi"); + gpio_request(plat->miso.gpio, "soft_spi_miso"); + + gpio_direction_output(plat->sclk.gpio, slave->mode & SPI_CPOL); + gpio_direction_output(plat->mosi.gpio, 1); + gpio_direction_input(plat->miso.gpio); + gpio_direction_output(plat->cs.gpio, !(slave->mode & SPI_CS_HIGH)); + + return 0; +} + +static const struct udevice_id soft_spi_ids[] = { + { .compatible = "u-boot,soft-spi" }, + { } +}; + +U_BOOT_DRIVER(soft_spi) = { + .name = "soft_spi", + .id = UCLASS_SPI, + .of_match = soft_spi_ids, + .ops = &soft_spi_ops, + .ofdata_to_platdata = soft_spi_ofdata_to_platdata, + .platdata_auto_alloc_size = sizeof(struct soft_spi_platdata), + .priv_auto_alloc_size = sizeof(struct soft_spi_priv), + .per_child_auto_alloc_size = sizeof(struct spi_slave), + .probe = soft_spi_probe, + .child_pre_probe = soft_spi_child_pre_probe, +}; |