board/LaCie/common/cpld-gpio-bus.c

   1 /*
   2  * cpld-gpio-bus.c: provides support for the CPLD GPIO bus found on some LaCie
   3  * boards (as the 2Big/5Big Network v2 and the 2Big NAS). This parallel GPIO
   4  * bus exposes two registers (address and data). Each of this register is made
   5  * up of several dedicated GPIOs. An extra GPIO is used to notify the CPLD that
   6  * the registers have been updated.
   7  *
   8  * Mostly this bus is used to configure the LEDs on LaCie boards.
   9  *
  10  * Copyright (C) 2013 Simon Guinot <simon.guinot@sequanux.org>
  11  *
  12  * SPDX-License-Identifier:     GPL-2.0+
  13  */
  14
  15 #include <asm/arch/gpio.h>
  16 #include "cpld-gpio-bus.h"
  17
  18 static void cpld_gpio_bus_set_addr(struct cpld_gpio_bus *bus, unsigned addr)
  19 {
  20         int pin;
  21
  22         for (pin = 0; pin < bus->num_addr; pin++)
  23                 kw_gpio_set_value(bus->addr[pin], (addr >> pin) & 1);
  24 }
  25
  26 static void cpld_gpio_bus_set_data(struct cpld_gpio_bus *bus, unsigned data)
  27 {
  28         int pin;
  29
  30         for (pin = 0; pin < bus->num_data; pin++)
  31                 kw_gpio_set_value(bus->data[pin], (data >> pin) & 1);
  32 }
  33
  34 static void cpld_gpio_bus_enable_select(struct cpld_gpio_bus *bus)
  35 {
  36         /* The transfer is enabled on the raising edge. */
  37         kw_gpio_set_value(bus->enable, 0);
  38         kw_gpio_set_value(bus->enable, 1);
  39 }
  40
  41 void cpld_gpio_bus_write(struct cpld_gpio_bus *bus,
  42                          unsigned addr, unsigned value)
  43 {
  44         cpld_gpio_bus_set_addr(bus, addr);
  45         cpld_gpio_bus_set_data(bus, value);
  46         cpld_gpio_bus_enable_select(bus);
  47 }