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f-stack/freebsd/arm/freescale/imx/imx_i2c.c

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/*-
* Copyright (C) 2008-2009 Semihalf, Michal Hajduk
* Copyright (c) 2012, 2013 The FreeBSD Foundation
* Copyright (c) 2015 Ian Lepore <ian@FreeBSD.org>
* All rights reserved.
*
* Portions of this software were developed by Oleksandr Rybalko
* under sponsorship from the FreeBSD Foundation.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
/*
* I2C driver for Freescale i.MX hardware.
*
* Note that the hardware is capable of running as both a master and a slave.
* This driver currently implements only master-mode operations.
*
* This driver supports multi-master i2c busses, by detecting bus arbitration
* loss and returning IIC_EBUSBSY status. Notably, it does not do any kind of
* retries if some other master jumps onto the bus and interrupts one of our
* transfer cycles resulting in arbitration loss in mid-transfer. The caller
* must handle retries in a way that makes sense for the slave being addressed.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/bus.h>
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/module.h>
#include <sys/resource.h>
#include <machine/bus.h>
#include <machine/resource.h>
#include <sys/rman.h>
#include <arm/freescale/imx/imx_ccmvar.h>
#include <dev/iicbus/iiconf.h>
#include <dev/iicbus/iicbus.h>
#include "iicbus_if.h"
#include <dev/fdt/fdt_common.h>
#include <dev/ofw/openfirm.h>
#include <dev/ofw/ofw_bus.h>
#include <dev/ofw/ofw_bus_subr.h>
#define I2C_ADDR_REG 0x00 /* I2C slave address register */
#define I2C_FDR_REG 0x04 /* I2C frequency divider register */
#define I2C_CONTROL_REG 0x08 /* I2C control register */
#define I2C_STATUS_REG 0x0C /* I2C status register */
#define I2C_DATA_REG 0x10 /* I2C data register */
#define I2C_DFSRR_REG 0x14 /* I2C Digital Filter Sampling rate */
#define I2CCR_MEN (1 << 7) /* Module enable */
#define I2CCR_MSTA (1 << 5) /* Master/slave mode */
#define I2CCR_MTX (1 << 4) /* Transmit/receive mode */
#define I2CCR_TXAK (1 << 3) /* Transfer acknowledge */
#define I2CCR_RSTA (1 << 2) /* Repeated START */
#define I2CSR_MCF (1 << 7) /* Data transfer */
#define I2CSR_MASS (1 << 6) /* Addressed as a slave */
#define I2CSR_MBB (1 << 5) /* Bus busy */
#define I2CSR_MAL (1 << 4) /* Arbitration lost */
#define I2CSR_SRW (1 << 2) /* Slave read/write */
#define I2CSR_MIF (1 << 1) /* Module interrupt */
#define I2CSR_RXAK (1 << 0) /* Received acknowledge */
#define I2C_BAUD_RATE_FAST 0x31
#define I2C_BAUD_RATE_DEF 0x3F
#define I2C_DFSSR_DIV 0x10
/*
* A table of available divisors and the associated coded values to put in the
* FDR register to achieve that divisor.. There is no algorithmic relationship I
* can see between divisors and the codes that go into the register. The table
* begins and ends with entries that handle insane configuration values.
*/
struct clkdiv {
u_int divisor;
u_int regcode;
};
static struct clkdiv clkdiv_table[] = {
{ 0, 0x20 }, { 22, 0x20 }, { 24, 0x21 }, { 26, 0x22 },
{ 28, 0x23 }, { 30, 0x00 }, { 32, 0x24 }, { 36, 0x25 },
{ 40, 0x26 }, { 42, 0x03 }, { 44, 0x27 }, { 48, 0x28 },
{ 52, 0x05 }, { 56, 0x29 }, { 60, 0x06 }, { 64, 0x2a },
{ 72, 0x2b }, { 80, 0x2c }, { 88, 0x09 }, { 96, 0x2d },
{ 104, 0x0a }, { 112, 0x2e }, { 128, 0x2f }, { 144, 0x0c },
{ 160, 0x30 }, { 192, 0x31 }, { 224, 0x32 }, { 240, 0x0f },
{ 256, 0x33 }, { 288, 0x10 }, { 320, 0x34 }, { 384, 0x35 },
{ 448, 0x36 }, { 480, 0x13 }, { 512, 0x37 }, { 576, 0x14 },
{ 640, 0x38 }, { 768, 0x39 }, { 896, 0x3a }, { 960, 0x17 },
{ 1024, 0x3b }, { 1152, 0x18 }, { 1280, 0x3c }, { 1536, 0x3d },
{ 1792, 0x3e }, { 1920, 0x1b }, { 2048, 0x3f }, { 2304, 0x1c },
{ 2560, 0x1d }, { 3072, 0x1e }, { 3840, 0x1f }, {UINT_MAX, 0x1f}
};
static struct ofw_compat_data compat_data[] = {
{"fsl,imx6q-i2c", 1},
{"fsl,imx-i2c", 1},
{NULL, 0}
};
struct i2c_softc {
device_t dev;
device_t iicbus;
struct resource *res;
int rid;
sbintime_t byte_time_sbt;
};
static phandle_t i2c_get_node(device_t, device_t);
static int i2c_probe(device_t);
static int i2c_attach(device_t);
static int i2c_repeated_start(device_t, u_char, int);
static int i2c_start(device_t, u_char, int);
static int i2c_stop(device_t);
static int i2c_reset(device_t, u_char, u_char, u_char *);
static int i2c_read(device_t, char *, int, int *, int, int);
static int i2c_write(device_t, const char *, int, int *, int);
static device_method_t i2c_methods[] = {
DEVMETHOD(device_probe, i2c_probe),
DEVMETHOD(device_attach, i2c_attach),
/* OFW methods */
DEVMETHOD(ofw_bus_get_node, i2c_get_node),
DEVMETHOD(iicbus_callback, iicbus_null_callback),
DEVMETHOD(iicbus_repeated_start, i2c_repeated_start),
DEVMETHOD(iicbus_start, i2c_start),
DEVMETHOD(iicbus_stop, i2c_stop),
DEVMETHOD(iicbus_reset, i2c_reset),
DEVMETHOD(iicbus_read, i2c_read),
DEVMETHOD(iicbus_write, i2c_write),
DEVMETHOD(iicbus_transfer, iicbus_transfer_gen),
DEVMETHOD_END
};
static driver_t i2c_driver = {
"iichb",
i2c_methods,
sizeof(struct i2c_softc),
};
static devclass_t i2c_devclass;
DRIVER_MODULE(i2c, simplebus, i2c_driver, i2c_devclass, 0, 0);
DRIVER_MODULE(iicbus, i2c, iicbus_driver, iicbus_devclass, 0, 0);
static phandle_t
i2c_get_node(device_t bus, device_t dev)
{
/*
* Share controller node with iicbus device
*/
return ofw_bus_get_node(bus);
}
static __inline void
i2c_write_reg(struct i2c_softc *sc, bus_size_t off, uint8_t val)
{
bus_write_1(sc->res, off, val);
}
static __inline uint8_t
i2c_read_reg(struct i2c_softc *sc, bus_size_t off)
{
return (bus_read_1(sc->res, off));
}
static __inline void
i2c_flag_set(struct i2c_softc *sc, bus_size_t off, uint8_t mask)
{
uint8_t status;
status = i2c_read_reg(sc, off);
status |= mask;
i2c_write_reg(sc, off, status);
}
/* Wait for bus to become busy or not-busy. */
static int
wait_for_busbusy(struct i2c_softc *sc, int wantbusy)
{
int retry, srb;
retry = 1000;
while (retry --) {
srb = i2c_read_reg(sc, I2C_STATUS_REG) & I2CSR_MBB;
if ((srb && wantbusy) || (!srb && !wantbusy))
return (IIC_NOERR);
DELAY(1);
}
return (IIC_ETIMEOUT);
}
/* Wait for transfer to complete, optionally check RXAK. */
static int
wait_for_xfer(struct i2c_softc *sc, int checkack)
{
int retry, sr;
/*
* Sleep for about the time it takes to transfer a byte (with precision
* set to tolerate 5% oversleep). We calculate the approximate byte
* transfer time when we set the bus speed divisor. Slaves are allowed
* to do clock-stretching so the actual transfer time can be larger, but
* this gets the bulk of the waiting out of the way without tying up the
* processor the whole time.
*/
pause_sbt("imxi2c", sc->byte_time_sbt, sc->byte_time_sbt / 20, 0);
retry = 10000;
while (retry --) {
sr = i2c_read_reg(sc, I2C_STATUS_REG);
if (sr & I2CSR_MIF) {
if (sr & I2CSR_MAL)
return (IIC_EBUSERR);
else if (checkack && (sr & I2CSR_RXAK))
return (IIC_ENOACK);
else
return (IIC_NOERR);
}
DELAY(1);
}
return (IIC_ETIMEOUT);
}
/*
* Implement the error handling shown in the state diagram of the imx6 reference
* manual. If there was an error, then:
* - Clear master mode (MSTA and MTX).
* - Wait for the bus to become free or for a timeout to happen.
* - Disable the controller.
*/
static int
i2c_error_handler(struct i2c_softc *sc, int error)
{
if (error != 0) {
i2c_write_reg(sc, I2C_STATUS_REG, 0);
i2c_write_reg(sc, I2C_CONTROL_REG, I2CCR_MEN);
wait_for_busbusy(sc, false);
i2c_write_reg(sc, I2C_CONTROL_REG, 0);
}
return (error);
}
static int
i2c_probe(device_t dev)
{
if (!ofw_bus_status_okay(dev))
return (ENXIO);
if (ofw_bus_search_compatible(dev, compat_data)->ocd_data == 0)
return (ENXIO);
device_set_desc(dev, "Freescale i.MX I2C");
return (BUS_PROBE_DEFAULT);
}
static int
i2c_attach(device_t dev)
{
struct i2c_softc *sc;
sc = device_get_softc(dev);
sc->dev = dev;
sc->rid = 0;
sc->res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &sc->rid,
RF_ACTIVE);
if (sc->res == NULL) {
device_printf(dev, "could not allocate resources");
return (ENXIO);
}
sc->iicbus = device_add_child(dev, "iicbus", -1);
if (sc->iicbus == NULL) {
device_printf(dev, "could not add iicbus child");
return (ENXIO);
}
bus_generic_attach(dev);
return (0);
}
static int
i2c_repeated_start(device_t dev, u_char slave, int timeout)
{
struct i2c_softc *sc;
int error;
sc = device_get_softc(dev);
if ((i2c_read_reg(sc, I2C_STATUS_REG) & I2CSR_MBB) == 0) {
return (IIC_EBUSERR);
}
/*
* Set repeated start condition, delay (per reference manual, min 156nS)
* before writing slave address, wait for ack after write.
*/
i2c_flag_set(sc, I2C_CONTROL_REG, I2CCR_RSTA);
DELAY(1);
i2c_write_reg(sc, I2C_STATUS_REG, 0x0);
i2c_write_reg(sc, I2C_DATA_REG, slave);
error = wait_for_xfer(sc, true);
return (i2c_error_handler(sc, error));
}
static int
i2c_start(device_t dev, u_char slave, int timeout)
{
struct i2c_softc *sc;
int error;
sc = device_get_softc(dev);
i2c_write_reg(sc, I2C_CONTROL_REG, I2CCR_MEN);
DELAY(10); /* Delay for controller to sample bus state. */
if (i2c_read_reg(sc, I2C_STATUS_REG) & I2CSR_MBB) {
return (i2c_error_handler(sc, IIC_EBUSERR));
}
i2c_write_reg(sc, I2C_CONTROL_REG, I2CCR_MEN | I2CCR_MSTA | I2CCR_MTX);
if ((error = wait_for_busbusy(sc, true)) != IIC_NOERR)
return (i2c_error_handler(sc, error));
i2c_write_reg(sc, I2C_STATUS_REG, 0);
i2c_write_reg(sc, I2C_DATA_REG, slave);
error = wait_for_xfer(sc, true);
return (i2c_error_handler(sc, error));
}
static int
i2c_stop(device_t dev)
{
struct i2c_softc *sc;
sc = device_get_softc(dev);
i2c_write_reg(sc, I2C_CONTROL_REG, I2CCR_MEN);
wait_for_busbusy(sc, false);
i2c_write_reg(sc, I2C_CONTROL_REG, 0);
return (IIC_NOERR);
}
static int
i2c_reset(device_t dev, u_char speed, u_char addr, u_char *oldadr)
{
struct i2c_softc *sc;
u_int busfreq, div, i, ipgfreq;
sc = device_get_softc(dev);
/*
* Look up the divisor that gives the nearest speed that doesn't exceed
* the configured value for the bus.
*/
ipgfreq = imx_ccm_ipg_hz();
busfreq = IICBUS_GET_FREQUENCY(sc->iicbus, speed);
div = howmany(ipgfreq, busfreq);
for (i = 0; i < nitems(clkdiv_table); i++) {
if (clkdiv_table[i].divisor >= div)
break;
}
/*
* Calculate roughly how long it will take to transfer a byte (which
* requires 9 clock cycles) at the new bus speed. This value is used to
* pause() while waiting for transfer-complete. With a 66MHz IPG clock
* and the actual i2c bus speeds that leads to, for nominal 100KHz and
* 400KHz bus speeds the transfer times are roughly 104uS and 22uS.
*/
busfreq = ipgfreq / clkdiv_table[i].divisor;
sc->byte_time_sbt = SBT_1US * (9000000 / busfreq);
/*
* Disable the controller (do the reset), and set the new clock divisor.
*/
i2c_write_reg(sc, I2C_STATUS_REG, 0x0);
i2c_write_reg(sc, I2C_CONTROL_REG, 0x0);
i2c_write_reg(sc, I2C_FDR_REG, (uint8_t)clkdiv_table[i].regcode);
return (IIC_NOERR);
}
static int
i2c_read(device_t dev, char *buf, int len, int *read, int last, int delay)
{
struct i2c_softc *sc;
int error, reg;
sc = device_get_softc(dev);
*read = 0;
if (len) {
if (len == 1)
i2c_write_reg(sc, I2C_CONTROL_REG, I2CCR_MEN |
I2CCR_MSTA | I2CCR_TXAK);
else
i2c_write_reg(sc, I2C_CONTROL_REG, I2CCR_MEN |
I2CCR_MSTA);
/* Dummy read to prime the receiver. */
i2c_write_reg(sc, I2C_STATUS_REG, 0x0);
i2c_read_reg(sc, I2C_DATA_REG);
}
error = 0;
*read = 0;
while (*read < len) {
if ((error = wait_for_xfer(sc, false)) != IIC_NOERR)
break;
i2c_write_reg(sc, I2C_STATUS_REG, 0x0);
if (last) {
if (*read == len - 2) {
/* NO ACK on last byte */
i2c_write_reg(sc, I2C_CONTROL_REG, I2CCR_MEN |
I2CCR_MSTA | I2CCR_TXAK);
} else if (*read == len - 1) {
/* Transfer done, signal stop. */
i2c_write_reg(sc, I2C_CONTROL_REG, I2CCR_MEN |
I2CCR_TXAK);
wait_for_busbusy(sc, false);
}
}
reg = i2c_read_reg(sc, I2C_DATA_REG);
*buf++ = reg;
(*read)++;
}
return (i2c_error_handler(sc, error));
}
static int
i2c_write(device_t dev, const char *buf, int len, int *sent, int timeout)
{
struct i2c_softc *sc;
int error;
sc = device_get_softc(dev);
error = 0;
*sent = 0;
while (*sent < len) {
i2c_write_reg(sc, I2C_STATUS_REG, 0x0);
i2c_write_reg(sc, I2C_DATA_REG, *buf++);
if ((error = wait_for_xfer(sc, true)) != IIC_NOERR)
break;
(*sent)++;
}
return (i2c_error_handler(sc, error));
}
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