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// SPDX-License-Identifier: GPL-2.0+
/*
* Driver for one wire controller in some i.MX Socs
*
* There are currently two silicon variants:
* V1: i.MX21, i.MX27, i.MX31, i.MX51
* V2: i.MX25, i.MX35, i.MX50, i.MX53
* Newer i.MX SoCs such as the i.MX6 do not have one wire controllers.
*
* The V1 controller only supports single bit operations.
* The V2 controller is backwards compatible on the register level but adds
* byte size operations and a "search ROM accelerator mode"
*
* This driver does not currently support the search ROM accelerator
*
* Copyright (c) 2018 Flowbird
* Martin Fuzzey <martin.fuzzey@flowbird.group>
*/
#include <asm/arch/clock.h>
#include <dm.h>
#include <dm/device_compat.h>
#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <w1.h>
struct mxc_w1_regs {
u16 control;
#define MXC_W1_CONTROL_RPP BIT(7)
#define MXC_W1_CONTROL_PST BIT(6)
#define MXC_W1_CONTROL_WR(x) BIT(5 - (x))
#define MXC_W1_CONTROL_RDST BIT(3)
u16 time_divider;
u16 reset;
/* Registers below on V2 silicon only */
u16 command;
u16 tx_rx;
u16 interrupt;
#define MXC_W1_INTERRUPT_TBE BIT(2)
#define MXC_W1_INTERRUPT_TSRE BIT(3)
#define MXC_W1_INTERRUPT_RBF BIT(4)
#define MXC_W1_INTERRUPT_RSRF BIT(5)
u16 interrupt_en;
};
struct mxc_w1_pdata {
struct mxc_w1_regs *regs;
};
/*
* this is the low level routine to read/write a bit on the One Wire
* interface on the hardware. It does write 0 if parameter bit is set
* to 0, otherwise a write 1/read.
*/
static u8 mxc_w1_touch_bit(struct mxc_w1_pdata *pdata, u8 bit)
{
u16 *ctrl_addr = &pdata->regs->control;
u16 mask = MXC_W1_CONTROL_WR(bit);
unsigned int timeout_cnt = 400; /* Takes max. 120us according to
* datasheet.
*/
writew(mask, ctrl_addr);
while (timeout_cnt--) {
if (!(readw(ctrl_addr) & mask))
break;
udelay(1);
}
return (readw(ctrl_addr) & MXC_W1_CONTROL_RDST) ? 1 : 0;
}
static u8 mxc_w1_read_byte(struct udevice *dev)
{
struct mxc_w1_pdata *pdata = dev_get_plat(dev);
struct mxc_w1_regs *regs = pdata->regs;
u16 status;
if (dev_get_driver_data(dev) < 2) {
int i;
u8 ret = 0;
for (i = 0; i < 8; i++)
ret |= (mxc_w1_touch_bit(pdata, 1) << i);
return ret;
}
readw(®s->tx_rx);
writew(0xFF, ®s->tx_rx);
do {
udelay(1); /* Without this bytes are sometimes duplicated... */
status = readw(®s->interrupt);
} while (!(status & MXC_W1_INTERRUPT_RBF));
return (u8)readw(®s->tx_rx);
}
static void mxc_w1_write_byte(struct udevice *dev, u8 byte)
{
struct mxc_w1_pdata *pdata = dev_get_plat(dev);
struct mxc_w1_regs *regs = pdata->regs;
u16 status;
if (dev_get_driver_data(dev) < 2) {
int i;
for (i = 0; i < 8; i++)
mxc_w1_touch_bit(pdata, (byte >> i) & 0x1);
return;
}
readw(®s->tx_rx);
writew(byte, ®s->tx_rx);
do {
udelay(1);
status = readw(®s->interrupt);
} while (!(status & MXC_W1_INTERRUPT_TSRE));
}
static bool mxc_w1_reset(struct udevice *dev)
{
struct mxc_w1_pdata *pdata = dev_get_plat(dev);
u16 reg_val;
writew(MXC_W1_CONTROL_RPP, &pdata->regs->control);
do {
reg_val = readw(&pdata->regs->control);
} while (reg_val & MXC_W1_CONTROL_RPP);
return !(reg_val & MXC_W1_CONTROL_PST);
}
static u8 mxc_w1_triplet(struct udevice *dev, bool bdir)
{
struct mxc_w1_pdata *pdata = dev_get_plat(dev);
u8 id_bit = mxc_w1_touch_bit(pdata, 1);
u8 comp_bit = mxc_w1_touch_bit(pdata, 1);
u8 retval;
if (id_bit && comp_bit)
return 0x03; /* error */
if (!id_bit && !comp_bit) {
/* Both bits are valid, take the direction given */
retval = bdir ? 0x04 : 0;
} else {
/* Only one bit is valid, take that direction */
bdir = id_bit;
retval = id_bit ? 0x05 : 0x02;
}
mxc_w1_touch_bit(pdata, bdir);
return retval;
}
static int mxc_w1_of_to_plat(struct udevice *dev)
{
struct mxc_w1_pdata *pdata = dev_get_plat(dev);
fdt_addr_t addr;
addr = dev_read_addr(dev);
if (addr == FDT_ADDR_T_NONE)
return -EINVAL;
pdata->regs = (struct mxc_w1_regs *)addr;
return 0;
};
static int mxc_w1_probe(struct udevice *dev)
{
struct mxc_w1_pdata *pdata = dev_get_plat(dev);
unsigned int clkrate = mxc_get_clock(MXC_IPG_PERCLK);
unsigned int clkdiv;
if (clkrate < 10000000) {
dev_err(dev, "input clock frequency (%u Hz) too low\n",
clkrate);
return -EINVAL;
}
clkdiv = clkrate / 1000000;
clkrate /= clkdiv;
if (clkrate < 980000 || clkrate > 1020000) {
dev_err(dev, "Incorrect time base frequency %u Hz\n", clkrate);
return -EINVAL;
}
writew(clkdiv - 1, &pdata->regs->time_divider);
return 0;
}
static const struct w1_ops mxc_w1_ops = {
.read_byte = mxc_w1_read_byte,
.reset = mxc_w1_reset,
.triplet = mxc_w1_triplet,
.write_byte = mxc_w1_write_byte,
};
static const struct udevice_id mxc_w1_id[] = {
{ .compatible = "fsl,imx21-owire", .data = 1 },
{ .compatible = "fsl,imx27-owire", .data = 1 },
{ .compatible = "fsl,imx31-owire", .data = 1 },
{ .compatible = "fsl,imx51-owire", .data = 1 },
{ .compatible = "fsl,imx25-owire", .data = 2 },
{ .compatible = "fsl,imx35-owire", .data = 2 },
{ .compatible = "fsl,imx50-owire", .data = 2 },
{ .compatible = "fsl,imx53-owire", .data = 2 },
{ },
};
U_BOOT_DRIVER(mxc_w1_drv) = {
.id = UCLASS_W1,
.name = "mxc_w1_drv",
.of_match = mxc_w1_id,
.of_to_plat = mxc_w1_of_to_plat,
.ops = &mxc_w1_ops,
.plat_auto = sizeof(struct mxc_w1_pdata),
.probe = mxc_w1_probe,
};
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