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u-boot/drivers/i2c/rcar_i2c.c
Adam Ford e53979cd34 i2c: rcar_i2c: Enable configuring SCL rise and fall times 
The Linux i2c driver supports i2c-scl-rising-time-ns,
and i2c-scl-falling-time-ns, but U-Boot uses hard-coded values
for these values.

Update the calculation by fetching them from the device tree if
present and use the previous values as the default if they are
missing.

Signed-off-by: Adam Ford <aford173@gmail.com>
Reviewed-by: Heiko Schocher <hs@denx.de>
2021-09-28 06:34:14 +02:00

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// SPDX-License-Identifier: GPL-2.0+
/*
* drivers/i2c/rcar_i2c.c
*
* Copyright (C) 2018 Marek Vasut <marek.vasut@gmail.com>
*
* Clock configuration based on Linux i2c-rcar.c:
* Copyright (C) 2014-15 Wolfram Sang <wsa@sang-engineering.com>
* Copyright (C) 2011-2015 Renesas Electronics Corporation
* Copyright (C) 2012-14 Renesas Solutions Corp.
* Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
*/
#include <common.h>
#include <clk.h>
#include <dm.h>
#include <i2c.h>
#include <asm/io.h>
#include <wait_bit.h>
#include <dm/device_compat.h>
#include <linux/bitops.h>
#include <linux/delay.h>
#define RCAR_I2C_ICSCR 0x00 /* slave ctrl */
#define RCAR_I2C_ICMCR 0x04 /* master ctrl */
#define RCAR_I2C_ICMCR_MDBS BIT(7) /* non-fifo mode switch */
#define RCAR_I2C_ICMCR_FSCL BIT(6) /* override SCL pin */
#define RCAR_I2C_ICMCR_FSDA BIT(5) /* override SDA pin */
#define RCAR_I2C_ICMCR_OBPC BIT(4) /* override pins */
#define RCAR_I2C_ICMCR_MIE BIT(3) /* master if enable */
#define RCAR_I2C_ICMCR_TSBE BIT(2)
#define RCAR_I2C_ICMCR_FSB BIT(1) /* force stop bit */
#define RCAR_I2C_ICMCR_ESG BIT(0) /* enable start bit gen */
#define RCAR_I2C_ICSSR 0x08 /* slave status */
#define RCAR_I2C_ICMSR 0x0c /* master status */
#define RCAR_I2C_ICMSR_MASK 0x7f
#define RCAR_I2C_ICMSR_MNR BIT(6) /* Nack */
#define RCAR_I2C_ICMSR_MAL BIT(5) /* Arbitration lost */
#define RCAR_I2C_ICMSR_MST BIT(4) /* Stop */
#define RCAR_I2C_ICMSR_MDE BIT(3)
#define RCAR_I2C_ICMSR_MDT BIT(2)
#define RCAR_I2C_ICMSR_MDR BIT(1)
#define RCAR_I2C_ICMSR_MAT BIT(0)
#define RCAR_I2C_ICSIER 0x10 /* slave irq enable */
#define RCAR_I2C_ICMIER 0x14 /* master irq enable */
#define RCAR_I2C_ICCCR 0x18 /* clock dividers */
#define RCAR_I2C_ICCCR_SCGD_OFF 3
#define RCAR_I2C_ICSAR 0x1c /* slave address */
#define RCAR_I2C_ICMAR 0x20 /* master address */
#define RCAR_I2C_ICRXD_ICTXD 0x24 /* data port */
/*
* First Bit Setup Cycle (Gen3).
* Defines 1st bit delay between SDA and SCL.
*/
#define RCAR_I2C_ICFBSCR 0x38
#define RCAR_I2C_ICFBSCR_TCYC17 0x0f /* 17*Tcyc */
enum rcar_i2c_type {
RCAR_I2C_TYPE_GEN2,
RCAR_I2C_TYPE_GEN3,
};
struct rcar_i2c_priv {
void __iomem *base;
struct clk clk;
u32 fall_ns;
u32 rise_ns;
u32 intdelay;
u32 icccr;
enum rcar_i2c_type type;
};
static int rcar_i2c_finish(struct udevice *dev)
{
struct rcar_i2c_priv *priv = dev_get_priv(dev);
int ret;
ret = wait_for_bit_le32(priv->base + RCAR_I2C_ICMSR, RCAR_I2C_ICMSR_MST,
true, 10, true);
writel(0, priv->base + RCAR_I2C_ICSSR);
writel(0, priv->base + RCAR_I2C_ICMSR);
writel(0, priv->base + RCAR_I2C_ICMCR);
return ret;
}
static int rcar_i2c_recover(struct udevice *dev)
{
struct rcar_i2c_priv *priv = dev_get_priv(dev);
u32 mcr = RCAR_I2C_ICMCR_MDBS | RCAR_I2C_ICMCR_OBPC;
u32 mcra = mcr | RCAR_I2C_ICMCR_FSDA;
int i;
u32 mstat;
/* Send 9 SCL pulses */
for (i = 0; i < 9; i++) {
writel(mcra | RCAR_I2C_ICMCR_FSCL, priv->base + RCAR_I2C_ICMCR);
udelay(5);
writel(mcra, priv->base + RCAR_I2C_ICMCR);
udelay(5);
}
/* Send stop condition */
udelay(5);
writel(mcra, priv->base + RCAR_I2C_ICMCR);
udelay(5);
writel(mcr, priv->base + RCAR_I2C_ICMCR);
udelay(5);
writel(mcr | RCAR_I2C_ICMCR_FSCL, priv->base + RCAR_I2C_ICMCR);
udelay(5);
writel(mcra | RCAR_I2C_ICMCR_FSCL, priv->base + RCAR_I2C_ICMCR);
udelay(5);
mstat = readl(priv->base + RCAR_I2C_ICMSR);
return mstat & RCAR_I2C_ICMCR_FSDA ? -EBUSY : 0;
}
static int rcar_i2c_set_addr(struct udevice *dev, u8 chip, u8 read)
{
struct rcar_i2c_priv *priv = dev_get_priv(dev);
u32 mask = RCAR_I2C_ICMSR_MAT |
(read ? RCAR_I2C_ICMSR_MDR : RCAR_I2C_ICMSR_MDE);
int ret;
writel(0, priv->base + RCAR_I2C_ICMIER);
writel(RCAR_I2C_ICMCR_MDBS, priv->base + RCAR_I2C_ICMCR);
writel(0, priv->base + RCAR_I2C_ICMSR);
writel(priv->icccr, priv->base + RCAR_I2C_ICCCR);
/* Wait for the bus */
ret = wait_for_bit_le32(priv->base + RCAR_I2C_ICMCR,
RCAR_I2C_ICMCR_FSDA, false, 2, true);
if (ret) {
if (rcar_i2c_recover(dev)) {
dev_err(dev, "Bus busy, aborting\n");
return ret;
}
}
writel((chip << 1) | read, priv->base + RCAR_I2C_ICMAR);
/* Reset */
writel(RCAR_I2C_ICMCR_MDBS | RCAR_I2C_ICMCR_MIE | RCAR_I2C_ICMCR_ESG,
priv->base + RCAR_I2C_ICMCR);
/* Clear Status */
writel(0, priv->base + RCAR_I2C_ICMSR);
ret = wait_for_bit_le32(priv->base + RCAR_I2C_ICMSR, mask,
true, 100, true);
if (ret)
return ret;
/* Check NAK */
if (readl(priv->base + RCAR_I2C_ICMSR) & RCAR_I2C_ICMSR_MNR)
return -EREMOTEIO;
return 0;
}
static int rcar_i2c_read_common(struct udevice *dev, struct i2c_msg *msg)
{
struct rcar_i2c_priv *priv = dev_get_priv(dev);
u32 icmcr = RCAR_I2C_ICMCR_MDBS | RCAR_I2C_ICMCR_MIE;
int i, ret = -EREMOTEIO;
for (i = 0; i < msg->len; i++) {
if (msg->len - 1 == i)
icmcr |= RCAR_I2C_ICMCR_FSB;
writel(icmcr, priv->base + RCAR_I2C_ICMCR);
writel((u32)~RCAR_I2C_ICMSR_MDR, priv->base + RCAR_I2C_ICMSR);
ret = wait_for_bit_le32(priv->base + RCAR_I2C_ICMSR,
RCAR_I2C_ICMSR_MDR, true, 100, true);
if (ret)
return ret;
msg->buf[i] = readl(priv->base + RCAR_I2C_ICRXD_ICTXD) & 0xff;
}
writel((u32)~RCAR_I2C_ICMSR_MDR, priv->base + RCAR_I2C_ICMSR);
return rcar_i2c_finish(dev);
}
static int rcar_i2c_write_common(struct udevice *dev, struct i2c_msg *msg)
{
struct rcar_i2c_priv *priv = dev_get_priv(dev);
u32 icmcr = RCAR_I2C_ICMCR_MDBS | RCAR_I2C_ICMCR_MIE;
int i, ret = -EREMOTEIO;
for (i = 0; i < msg->len; i++) {
writel(msg->buf[i], priv->base + RCAR_I2C_ICRXD_ICTXD);
writel(icmcr, priv->base + RCAR_I2C_ICMCR);
writel((u32)~RCAR_I2C_ICMSR_MDE, priv->base + RCAR_I2C_ICMSR);
ret = wait_for_bit_le32(priv->base + RCAR_I2C_ICMSR,
RCAR_I2C_ICMSR_MDE, true, 100, true);
if (ret)
return ret;
}
writel((u32)~RCAR_I2C_ICMSR_MDE, priv->base + RCAR_I2C_ICMSR);
icmcr |= RCAR_I2C_ICMCR_FSB;
writel(icmcr, priv->base + RCAR_I2C_ICMCR);
return rcar_i2c_finish(dev);
}
static int rcar_i2c_xfer(struct udevice *dev, struct i2c_msg *msg, int nmsgs)
{
int ret;
for (; nmsgs > 0; nmsgs--, msg++) {
ret = rcar_i2c_set_addr(dev, msg->addr, !!(msg->flags & I2C_M_RD));
if (ret)
return ret;
if (msg->flags & I2C_M_RD)
ret = rcar_i2c_read_common(dev, msg);
else
ret = rcar_i2c_write_common(dev, msg);
if (ret)
return ret;
}
return 0;
}
static int rcar_i2c_probe_chip(struct udevice *dev, uint addr, uint flags)
{
struct rcar_i2c_priv *priv = dev_get_priv(dev);
int ret;
/* Ignore address 0, slave address */
if (addr == 0)
return -EINVAL;
ret = rcar_i2c_set_addr(dev, addr, 1);
writel(0, priv->base + RCAR_I2C_ICMSR);
return ret;
}
static int rcar_i2c_set_speed(struct udevice *dev, uint bus_freq_hz)
{
struct rcar_i2c_priv *priv = dev_get_priv(dev);
u32 scgd, cdf, round, ick, sum, scl;
unsigned long rate;
/*
* calculate SCL clock
* see
* ICCCR
*
* ick = clkp / (1 + CDF)
* SCL = ick / (20 + SCGD * 8 + F[(ticf + tr + intd) * ick])
*
* ick : I2C internal clock < 20 MHz
* ticf : I2C SCL falling time
* tr : I2C SCL rising time
* intd : LSI internal delay
* clkp : peripheral_clk
* F[] : integer up-valuation
*/
rate = clk_get_rate(&priv->clk);
cdf = rate / 20000000;
if (cdf >= 8) {
dev_err(dev, "Input clock %lu too high\n", rate);
return -EIO;
}
ick = rate / (cdf + 1);
/*
* it is impossible to calculate large scale
* number on u32. separate it
*
* F[(ticf + tr + intd) * ick] with sum = (ticf + tr + intd)
* = F[sum * ick / 1000000000]
* = F[(ick / 1000000) * sum / 1000]
*/
sum = priv->fall_ns + priv->rise_ns + priv->intdelay;
round = (ick + 500000) / 1000000 * sum;
round = (round + 500) / 1000;
/*
* SCL = ick / (20 + SCGD * 8 + F[(ticf + tr + intd) * ick])
*
* Calculation result (= SCL) should be less than
* bus_speed for hardware safety
*
* We could use something along the lines of
* div = ick / (bus_speed + 1) + 1;
* scgd = (div - 20 - round + 7) / 8;
* scl = ick / (20 + (scgd * 8) + round);
* (not fully verified) but that would get pretty involved
*/
for (scgd = 0; scgd < 0x40; scgd++) {
scl = ick / (20 + (scgd * 8) + round);
if (scl <= bus_freq_hz)
goto scgd_find;
}
dev_err(dev, "it is impossible to calculate best SCL\n");
return -EIO;
scgd_find:
dev_dbg(dev, "clk %d/%d(%lu), round %u, CDF:0x%x, SCGD: 0x%x\n",
scl, bus_freq_hz, clk_get_rate(&priv->clk), round, cdf, scgd);
priv->icccr = (scgd << RCAR_I2C_ICCCR_SCGD_OFF) | cdf;
writel(priv->icccr, priv->base + RCAR_I2C_ICCCR);
if (priv->type == RCAR_I2C_TYPE_GEN3) {
/* Set SCL/SDA delay */
writel(RCAR_I2C_ICFBSCR_TCYC17, priv->base + RCAR_I2C_ICFBSCR);
}
return 0;
}
static int rcar_i2c_probe(struct udevice *dev)
{
struct rcar_i2c_priv *priv = dev_get_priv(dev);
int ret;
priv->base = dev_read_addr_ptr(dev);
priv->rise_ns = dev_read_u32_default(dev,
"i2c-scl-rising-time-ns", 200);
priv->fall_ns = dev_read_u32_default(dev,
"i2c-scl-falling-time-ns", 35);
priv->intdelay = dev_read_u32_default(dev,
"i2c-scl-internal-delay-ns", 5);
priv->type = dev_get_driver_data(dev);
ret = clk_get_by_index(dev, 0, &priv->clk);
if (ret)
return ret;
ret = clk_enable(&priv->clk);
if (ret)
return ret;
/* reset slave mode */
writel(0, priv->base + RCAR_I2C_ICSIER);
writel(0, priv->base + RCAR_I2C_ICSAR);
writel(0, priv->base + RCAR_I2C_ICSCR);
writel(0, priv->base + RCAR_I2C_ICSSR);
/* reset master mode */
writel(0, priv->base + RCAR_I2C_ICMIER);
writel(0, priv->base + RCAR_I2C_ICMCR);
writel(0, priv->base + RCAR_I2C_ICMSR);
writel(0, priv->base + RCAR_I2C_ICMAR);
ret = rcar_i2c_set_speed(dev, I2C_SPEED_STANDARD_RATE);
if (ret)
clk_disable(&priv->clk);
return ret;
}
static const struct dm_i2c_ops rcar_i2c_ops = {
.xfer = rcar_i2c_xfer,
.probe_chip = rcar_i2c_probe_chip,
.set_bus_speed = rcar_i2c_set_speed,
};
static const struct udevice_id rcar_i2c_ids[] = {
{ .compatible = "renesas,rcar-gen2-i2c", .data = RCAR_I2C_TYPE_GEN2 },
{ .compatible = "renesas,rcar-gen3-i2c", .data = RCAR_I2C_TYPE_GEN3 },
{ }
};
U_BOOT_DRIVER(i2c_rcar) = {
.name = "i2c_rcar",
.id = UCLASS_I2C,
.of_match = rcar_i2c_ids,
.probe = rcar_i2c_probe,
.priv_auto = sizeof(struct rcar_i2c_priv),
.ops = &rcar_i2c_ops,
};
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