Introduce driver to support "fairchild,74hc595" devices. 1. Take linux drivers/drivers/gpio/gpio-74x164.c as reference. 2. Following the naming used in Linux driver with gen_7x164 as the prefix. 3. Enable CONFIG_DM_74X164 to use this driver. 4. Follow Documentation/devicetree/bindings/gpio/gpio-74x164.txt to add device nodes 5. Tested on i.MX6 UltraLite with 74LV595 using gpio command and oscillograph. Signed-off-by: Peng Fan <van.freenix@gmail.com> Cc: Simon Glass <sjg@chromium.org> Cc: Masahiro Yamada <yamada.masahiro@socionext.com> Cc: Chin Liang See <clsee@altera.com> Cc: Bhuvanchandra DV <bhuvanchandra.dv@toradex.com> Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com> Cc: Fabio Estevam <fabio.estevam@nxp.com> Cc: Stefano Babic <sbabic@denx.de> Reviewed-by: Simon Glass <sjg@chromium.org>master
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/*
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* Take drivers/gpio/gpio-74x164.c as reference. |
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* |
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* 74Hx164 - Generic serial-in/parallel-out 8-bits shift register GPIO driver |
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* |
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* Copyright (C) 2016 Peng Fan <van.freenix@gmail.com> |
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* |
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* SPDX-License-Identifier: GPL-2.0+ |
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* |
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*/ |
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#include <common.h> |
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#include <errno.h> |
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#include <dm.h> |
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#include <fdtdec.h> |
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#include <malloc.h> |
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#include <asm/gpio.h> |
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#include <asm/io.h> |
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#include <dt-bindings/gpio/gpio.h> |
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#include <spi.h> |
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DECLARE_GLOBAL_DATA_PTR; |
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/*
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* struct gen_74x164_chip - Data for 74Hx164 |
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* |
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* @oe: OE pin |
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* @nregs: number of registers |
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* @buffer: buffer for chained chips |
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*/ |
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#define GEN_74X164_NUMBER_GPIOS 8 |
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struct gen_74x164_priv { |
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struct gpio_desc oe; |
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u32 nregs; |
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/*
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* Since the nregs are chained, every byte sent will make |
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* the previous byte shift to the next register in the |
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* chain. Thus, the first byte sent will end up in the last |
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* register at the end of the transfer. So, to have a logical |
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* numbering, store the bytes in reverse order. |
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*/ |
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u8 *buffer; |
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}; |
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static int gen_74x164_write_conf(struct udevice *dev) |
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{ |
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struct gen_74x164_priv *priv = dev_get_priv(dev); |
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int ret; |
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ret = dm_spi_claim_bus(dev); |
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if (ret) |
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return ret; |
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ret = dm_spi_xfer(dev, priv->nregs * 8, priv->buffer, NULL, |
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SPI_XFER_BEGIN | SPI_XFER_END); |
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dm_spi_release_bus(dev); |
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return ret; |
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} |
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static int gen_74x164_get_value(struct udevice *dev, unsigned offset) |
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{ |
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struct gen_74x164_priv *priv = dev_get_priv(dev); |
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uint bank = priv->nregs - 1 - offset / 8; |
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uint pin = offset % 8; |
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return (priv->buffer[bank] >> pin) & 0x1; |
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} |
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static int gen_74x164_set_value(struct udevice *dev, unsigned offset, |
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int value) |
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{ |
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struct gen_74x164_priv *priv = dev_get_priv(dev); |
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uint bank = priv->nregs - 1 - offset / 8; |
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uint pin = offset % 8; |
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int ret; |
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if (value) |
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priv->buffer[bank] |= 1 << pin; |
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else |
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priv->buffer[bank] &= ~(1 << pin); |
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ret = gen_74x164_write_conf(dev); |
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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 gen_74x164_direction_input(struct udevice *dev, unsigned offset) |
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{ |
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return -ENOSYS; |
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} |
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static int gen_74x164_direction_output(struct udevice *dev, unsigned offset, |
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int value) |
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{ |
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return gen_74x164_set_value(dev, offset, value); |
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} |
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static int gen_74x164_get_function(struct udevice *dev, unsigned offset) |
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{ |
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return GPIOF_OUTPUT; |
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} |
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static int gen_74x164_xlate(struct udevice *dev, struct gpio_desc *desc, |
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struct fdtdec_phandle_args *args) |
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{ |
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desc->offset = args->args[0]; |
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desc->flags = args->args[1] & GPIO_ACTIVE_LOW ? GPIOD_ACTIVE_LOW : 0; |
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return 0; |
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} |
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static const struct dm_gpio_ops gen_74x164_ops = { |
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.direction_input = gen_74x164_direction_input, |
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.direction_output = gen_74x164_direction_output, |
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.get_value = gen_74x164_get_value, |
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.set_value = gen_74x164_set_value, |
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.get_function = gen_74x164_get_function, |
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.xlate = gen_74x164_xlate, |
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}; |
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static int gen_74x164_probe(struct udevice *dev) |
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{ |
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struct gen_74x164_priv *priv = dev_get_priv(dev); |
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struct gpio_dev_priv *uc_priv = dev_get_uclass_priv(dev); |
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char *str, name[32]; |
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int ret; |
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const void *fdt = gd->fdt_blob; |
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int node = dev->of_offset; |
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snprintf(name, sizeof(name), "%s_", dev->name); |
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str = strdup(name); |
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if (!str) |
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return -ENOMEM; |
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/*
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* See Linux kernel: |
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* Documentation/devicetree/bindings/gpio/gpio-74x164.txt |
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*/ |
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priv->nregs = fdtdec_get_int(fdt, node, "registers-number", 1); |
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priv->buffer = calloc(priv->nregs, sizeof(u8)); |
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if (!priv->buffer) { |
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ret = -ENOMEM; |
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goto free_str; |
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} |
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ret = fdtdec_get_byte_array(fdt, node, "registers-default", |
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priv->buffer, priv->nregs); |
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if (ret) |
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dev_dbg(dev, "No registers-default property\n"); |
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ret = gpio_request_by_name(dev, "oe-gpios", 0, &priv->oe, |
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GPIOD_IS_OUT | GPIOD_IS_OUT_ACTIVE); |
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if (ret) { |
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dev_err(dev, "No oe-pins property\n"); |
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goto free_buf; |
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} |
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uc_priv->bank_name = str; |
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uc_priv->gpio_count = priv->nregs * 8; |
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ret = gen_74x164_write_conf(dev); |
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if (ret) |
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goto free_buf; |
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dev_dbg(dev, "%s is ready\n", dev->name); |
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return 0; |
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free_buf: |
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free(priv->buffer); |
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free_str: |
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free(str); |
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return ret; |
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} |
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static const struct udevice_id gen_74x164_ids[] = { |
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{ .compatible = "fairchild,74hc595" }, |
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{ } |
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}; |
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U_BOOT_DRIVER(74x164) = { |
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.name = "74x164", |
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.id = UCLASS_GPIO, |
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.ops = &gen_74x164_ops, |
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.probe = gen_74x164_probe, |
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.priv_auto_alloc_size = sizeof(struct gen_74x164_priv), |
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.of_match = gen_74x164_ids, |
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}; |
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