Quelle  simatic-ipc-batt.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0
/*
 * Siemens SIMATIC IPC driver for CMOS battery monitoring
 *
 * Copyright (c) Siemens AG, 2023
 *
 * Authors:
 *  Gerd Haeussler <gerd.haeussler.ext@siemens.com>
 *  Henning Schild <henning.schild@siemens.com>
 */

#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt

#include <linux/delay.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/gpio/machine.h>
#include <linux/gpio/consumer.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/platform_data/x86/simatic-ipc-base.h>
#include <linux/sizes.h>

#include "simatic-ipc-batt.h"

#define BATT_DELAY_MS (1000 * 60 * 60 * 24) /* 24 h delay */

#define SIMATIC_IPC_BATT_LEVEL_FULL 3000
#define SIMATIC_IPC_BATT_LEVEL_CRIT 2750
#define SIMATIC_IPC_BATT_LEVEL_EMPTY    0

static struct simatic_ipc_batt {
 u8 devmode;
 long current_state;
 struct gpio_desc *gpios[3];
 unsigned long last_updated_jiffies;
} priv;

static long simatic_ipc_batt_read_gpio(void)
{
 long r = SIMATIC_IPC_BATT_LEVEL_FULL;

 if (priv.gpios[2]) {
  gpiod_set_value(priv.gpios[2], 1);
  msleep(150);
 }

 if (gpiod_get_value_cansleep(priv.gpios[0]))
  r = SIMATIC_IPC_BATT_LEVEL_EMPTY;
 else if (gpiod_get_value_cansleep(priv.gpios[1]))
  r = SIMATIC_IPC_BATT_LEVEL_CRIT;

 if (priv.gpios[2])
  gpiod_set_value(priv.gpios[2], 0);

 return r;
}

#define SIMATIC_IPC_BATT_PORT_BASE 0x404D
static struct resource simatic_ipc_batt_io_res =
 DEFINE_RES_IO_NAMED(SIMATIC_IPC_BATT_PORT_BASE, SZ_1, KBUILD_MODNAME);

static long simatic_ipc_batt_read_io(struct device *dev)
{
 long r = SIMATIC_IPC_BATT_LEVEL_FULL;
 struct resource *res = &simatic_ipc_batt_io_res;
 u8 val;

 if (!request_muxed_region(res->start, resource_size(res), res->name)) {
  dev_err(dev, "Unable to register IO resource at %pR\n", res);
  return -EBUSY;
 }

 val = inb(SIMATIC_IPC_BATT_PORT_BASE);
 release_region(simatic_ipc_batt_io_res.start, resource_size(&simatic_ipc_batt_io_res));

 if (val & (1 << 7))
  r = SIMATIC_IPC_BATT_LEVEL_EMPTY;
 else if (val & (1 << 6))
  r = SIMATIC_IPC_BATT_LEVEL_CRIT;

 return r;
}

static long simatic_ipc_batt_read_value(struct device *dev)
{
 unsigned long next_update;

 next_update = priv.last_updated_jiffies + msecs_to_jiffies(BATT_DELAY_MS);
 if (time_after(jiffies, next_update) || !priv.last_updated_jiffies) {
  if (priv.devmode == SIMATIC_IPC_DEVICE_227E)
   priv.current_state = simatic_ipc_batt_read_io(dev);
  else
   priv.current_state = simatic_ipc_batt_read_gpio();

  priv.last_updated_jiffies = jiffies;
  if (priv.current_state < SIMATIC_IPC_BATT_LEVEL_FULL)
   dev_warn(dev, "CMOS battery needs to be replaced.\n");
 }

 return priv.current_state;
}

static int simatic_ipc_batt_read(struct device *dev, enum hwmon_sensor_types type,
     u32 attr, int channel, long *val)
{
 switch (attr) {
 case hwmon_in_input:
  *val = simatic_ipc_batt_read_value(dev);
  break;
 case hwmon_in_lcrit:
  *val = SIMATIC_IPC_BATT_LEVEL_CRIT;
  break;
 default:
  return -EOPNOTSUPP;
 }

 return 0;
}

static umode_t simatic_ipc_batt_is_visible(const void *data, enum hwmon_sensor_types type,
        u32 attr, int channel)
{
 if (attr == hwmon_in_input || attr == hwmon_in_lcrit)
  return 0444;

 return 0;
}

static const struct hwmon_ops simatic_ipc_batt_ops = {
 .is_visible = simatic_ipc_batt_is_visible,
 .read = simatic_ipc_batt_read,
};

static const struct hwmon_channel_info *simatic_ipc_batt_info[] = {
 HWMON_CHANNEL_INFO(in, HWMON_I_INPUT | HWMON_I_LCRIT),
 NULL
};

static const struct hwmon_chip_info simatic_ipc_batt_chip_info = {
 .ops = &simatic_ipc_batt_ops,
 .info = simatic_ipc_batt_info,
};

void simatic_ipc_batt_remove(struct platform_device *pdev, struct gpiod_lookup_table *table)
{
 gpiod_remove_lookup_table(table);
}
EXPORT_SYMBOL_GPL(simatic_ipc_batt_remove);

int simatic_ipc_batt_probe(struct platform_device *pdev, struct gpiod_lookup_table *table)
{
 struct simatic_ipc_platform *plat;
 struct device *dev = &pdev->dev;
 struct device *hwmon_dev;
 unsigned long flags;
 int err;

 plat = pdev->dev.platform_data;
 priv.devmode = plat->devmode;

 switch (priv.devmode) {
 case SIMATIC_IPC_DEVICE_127E:
 case SIMATIC_IPC_DEVICE_227G:
 case SIMATIC_IPC_DEVICE_BX_39A:
 case SIMATIC_IPC_DEVICE_BX_21A:
 case SIMATIC_IPC_DEVICE_BX_59A:
  table->dev_id = dev_name(dev);
  gpiod_add_lookup_table(table);
  break;
 case SIMATIC_IPC_DEVICE_227E:
  goto nogpio;
 default:
  return -ENODEV;
 }

 priv.gpios[0] = devm_gpiod_get_index(dev, "CMOSBattery empty", 0, GPIOD_IN);
 if (IS_ERR(priv.gpios[0])) {
  err = PTR_ERR(priv.gpios[0]);
  priv.gpios[0] = NULL;
  goto out;
 }
 priv.gpios[1] = devm_gpiod_get_index(dev, "CMOSBattery low", 1, GPIOD_IN);
 if (IS_ERR(priv.gpios[1])) {
  err = PTR_ERR(priv.gpios[1]);
  priv.gpios[1] = NULL;
  goto out;
 }

 if (table->table[2].key) {
  flags = GPIOD_OUT_HIGH;
  if (priv.devmode == SIMATIC_IPC_DEVICE_BX_21A ||
      priv.devmode == SIMATIC_IPC_DEVICE_BX_59A)
   flags = GPIOD_OUT_LOW;
  priv.gpios[2] = devm_gpiod_get_index(dev, "CMOSBattery meter", 2, flags);
  if (IS_ERR(priv.gpios[2])) {
   err = PTR_ERR(priv.gpios[2]);
   priv.gpios[2] = NULL;
   goto out;
  }
 } else {
  priv.gpios[2] = NULL;
 }

nogpio:
 hwmon_dev = devm_hwmon_device_register_with_info(dev, KBUILD_MODNAME,
        &priv,
        &simatic_ipc_batt_chip_info,
        NULL);
 if (IS_ERR(hwmon_dev)) {
  err = PTR_ERR(hwmon_dev);
  goto out;
 }

 /* warn about aging battery even if userspace never reads hwmon */
 simatic_ipc_batt_read_value(dev);

 return 0;
out:
 simatic_ipc_batt_remove(pdev, table);

 return err;
}
EXPORT_SYMBOL_GPL(simatic_ipc_batt_probe);

static void simatic_ipc_batt_io_remove(struct platform_device *pdev)
{
 simatic_ipc_batt_remove(pdev, NULL);
}

static int simatic_ipc_batt_io_probe(struct platform_device *pdev)
{
 return simatic_ipc_batt_probe(pdev, NULL);
}

static struct platform_driver simatic_ipc_batt_driver = {
 .probe = simatic_ipc_batt_io_probe,
 .remove = simatic_ipc_batt_io_remove,
 .driver = {
  .name = KBUILD_MODNAME,
 },
};

module_platform_driver(simatic_ipc_batt_driver);

MODULE_DESCRIPTION("CMOS core battery driver for Siemens Simatic IPCs");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:" KBUILD_MODNAME);
MODULE_AUTHOR("Henning Schild ");