path: root/drivers/staging/ti-soc-thermal/ti-bandgap.c

/*
 * OMAP4 Bandgap temperature sensor driver
 *
 * Copyright (C) 2011-2012 Texas Instruments Incorporated - http://www.ti.com/
 * Author: J Keerthy <j-keerthy@ti.com>
 * Author: Moiz Sonasath <m-sonasath@ti.com>
 * Couple of fixes, DT and MFD adaptation:
 *   Eduardo Valentin <eduardo.valentin@ti.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * version 2 as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA
 *
 */

#include <linux/module.h>
#include <linux/export.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/clk.h>
#include <linux/gpio.h>
#include <linux/platform_device.h>
#include <linux/err.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/reboot.h>
#include <linux/of_device.h>
#include <linux/of_platform.h>
#include <linux/of_irq.h>
#include <linux/io.h>

#include "ti-bandgap.h"

/***   Helper functions to access registers and their bitfields   ***/

/**
 * omap_bandgap_readl() - simple read helper function
 * @bgp: pointer to omap_bandgap structure
 * @reg: desired register (offset) to be read
 *
 * Helper function to read bandgap registers. It uses the io remapped area.
 * Returns the register value.
 */
static u32 omap_bandgap_readl(struct omap_bandgap *bgp, u32 reg)
{
	return readl(bgp->base + reg);
}

/**
 * omap_bandgap_writel() - simple write helper function
 * @bgp: pointer to omap_bandgap structure
 * @val: desired register value to be written
 * @reg: desired register (offset) to be written
 *
 * Helper function to write bandgap registers. It uses the io remapped area.
 */
static void omap_bandgap_writel(struct omap_bandgap *bgp, u32 val, u32 reg)
{
	writel(val, bgp->base + reg);
}

/**
 * DOC: macro to update bits.
 *
 * RMW_BITS() - used to read, modify and update bandgap bitfields.
 *            The value passed will be shifted.
 */
#define RMW_BITS(bgp, id, reg, mask, val)			\
do {								\
	struct temp_sensor_registers *t;			\
	u32 r;							\
								\
	t = bgp->conf->sensors[(id)].registers;		\
	r = omap_bandgap_readl(bgp, t->reg);			\
	r &= ~t->mask;						\
	r |= (val) << __ffs(t->mask);				\
	omap_bandgap_writel(bgp, r, t->reg);			\
} while (0)

/***   Basic helper functions   ***/

/**
 * omap_bandgap_power() - controls the power state of a bandgap device
 * @bgp: pointer to omap_bandgap structure
 * @on: desired power state (1 - on, 0 - off)
 *
 * Used to power on/off a bandgap device instance. Only used on those
 * that features tempsoff bit.
 */
static int omap_bandgap_power(struct omap_bandgap *bgp, bool on)
{
	int i;

	if (!OMAP_BANDGAP_HAS(bgp, POWER_SWITCH))
		goto exit;

	for (i = 0; i < bgp->conf->sensor_count; i++)
		/* active on 0 */
		RMW_BITS(bgp, i, temp_sensor_ctrl, bgap_tempsoff_mask, !on);

exit:
	return 0;
}

/**
 * omap_bandgap_read_temp() - helper function to read sensor temperature
 * @bgp: pointer to omap_bandgap structure
 * @id: bandgap sensor id
 *
 * Function to concentrate the steps to read sensor temperature register.
 * This function is desired because, depending on bandgap device version,
 * it might be needed to freeze the bandgap state machine, before fetching
 * the register value.
 */
static u32 omap_bandgap_read_temp(struct omap_bandgap *bgp, int id)
{
	struct temp_sensor_registers *tsr;
	u32 temp, reg;

	tsr = bgp->conf->sensors[id].