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u-boot-brain/drivers/i2c/lpc32xx_i2c.c
Vladimir Zapolskiy ea16c6a13b i2c: lpc32xx: correct sanity check for requested bus speed 
LPC32xx has 3 I2C bus controllers, 2 of them are used as generic ones
and their parent clock is HCLK and CLK_HI/CLK_LO registers are 10 bit
wide. This means that if HCLK is 104MHz, then minimal configurable I2C
clock speed is about 51KHz.

Only USB OTG I2C bus controller CLK registers are 8 bit wide, thus in
assumption that peripheral clock is 13MHz it allows to set the minimal
bus speed about 25.5KHz.

Check for negative half clock value is removed since it is always false.

The change fixes the following problem for I2C busses 0 and 1:

  => i2c dev 0
  Setting bus to 0
  => i2c speed 100000
  Setting bus speed to 100000 Hz
  Failure changing bus speed (-22)

Signed-off-by: Vladimir Zapolskiy <vz@mleia.com>
Tested-by: Sylvain Lemieux <slemieux@tycoint.com>
2015-08-18 13:45:59 -04:00

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/*
* LPC32xx I2C interface driver
*
* (C) Copyright 2014-2015 DENX Software Engineering GmbH
* Written-by: Albert ARIBAUD - 3ADEV <albert.aribaud@3adev.fr>
*
* SPDX-License-Identifier: GPL-2.0+
*/
#include <common.h>
#include <asm/io.h>
#include <i2c.h>
#include <asm/errno.h>
#include <asm/arch/clk.h>
/*
* Provide default speed and slave if target did not
*/
#if !defined(CONFIG_SYS_I2C_LPC32XX_SPEED)
#define CONFIG_SYS_I2C_LPC32XX_SPEED 350000
#endif
#if !defined(CONFIG_SYS_I2C_LPC32XX_SLAVE)
#define CONFIG_SYS_I2C_LPC32XX_SLAVE 0
#endif
/* i2c register set */
struct lpc32xx_i2c_registers {
union {
u32 rx;
u32 tx;
};
u32 stat;
u32 ctrl;
u32 clk_hi;
u32 clk_lo;
u32 adr;
u32 rxfl;
u32 txfl;
u32 rxb;
u32 txb;
u32 stx;
u32 stxfl;
};
/* TX register fields */
#define LPC32XX_I2C_TX_START 0x00000100
#define LPC32XX_I2C_TX_STOP 0x00000200
/* Control register values */
#define LPC32XX_I2C_SOFT_RESET 0x00000100
/* Status register values */
#define LPC32XX_I2C_STAT_TFF 0x00000400
#define LPC32XX_I2C_STAT_RFE 0x00000200
#define LPC32XX_I2C_STAT_DRMI 0x00000008
#define LPC32XX_I2C_STAT_NAI 0x00000004
#define LPC32XX_I2C_STAT_TDI 0x00000001
static struct lpc32xx_i2c_registers *lpc32xx_i2c[] = {
(struct lpc32xx_i2c_registers *)I2C1_BASE,
(struct lpc32xx_i2c_registers *)I2C2_BASE,
(struct lpc32xx_i2c_registers *)(USB_BASE + 0x300)
};
/* Set I2C bus speed */
static unsigned int lpc32xx_i2c_set_bus_speed(struct i2c_adapter *adap,
unsigned int speed)
{
int half_period;
if (speed == 0)
return -EINVAL;
/* OTG I2C clock source and CLK registers are different */
if (adap->hwadapnr == 2) {
half_period = (get_periph_clk_rate() / speed) / 2;
if (half_period > 0xFF)
return -EINVAL;
} else {
half_period = (get_hclk_clk_rate() / speed) / 2;
if (half_period > 0x3FF)
return -EINVAL;
}
writel(half_period, &lpc32xx_i2c[adap->hwadapnr]->clk_hi);
writel(half_period, &lpc32xx_i2c[adap->hwadapnr]->clk_lo);
return 0;
}
/* I2C init called by cmd_i2c when doing 'i2c reset'. */
static void _i2c_init(struct i2c_adapter *adap,
int requested_speed, int slaveadd)
{
struct lpc32xx_i2c_registers *i2c = lpc32xx_i2c[adap->hwadapnr];
/* soft reset (auto-clears) */
writel(LPC32XX_I2C_SOFT_RESET, &i2c->ctrl);
/* set HI and LO periods for half of the default speed */
lpc32xx_i2c_set_bus_speed(adap, requested_speed);
}
/* I2C probe called by cmd_i2c when doing 'i2c probe'. */
static int lpc32xx_i2c_probe(struct i2c_adapter *adap, u8 dev)
{
struct lpc32xx_i2c_registers *i2c = lpc32xx_i2c[adap->hwadapnr];
int stat;
/* Soft-reset the controller */
writel(LPC32XX_I2C_SOFT_RESET, &i2c->ctrl);
while (readl(&i2c->ctrl) & LPC32XX_I2C_SOFT_RESET)
;
/* Addre slave for write with start before and stop after */
writel((dev<<1) | LPC32XX_I2C_TX_START | LPC32XX_I2C_TX_STOP,
&i2c->tx);
/* wait for end of transation */
while (!((stat = readl(&i2c->stat)) & LPC32XX_I2C_STAT_TDI))
;
/* was there no acknowledge? */
return (stat & LPC32XX_I2C_STAT_NAI) ? -1 : 0;
}
/*
* I2C read called by cmd_i2c when doing 'i2c read' and by cmd_eeprom.c
* Begin write, send address byte(s), begin read, receive data bytes, end.
*/
static int lpc32xx_i2c_read(struct i2c_adapter *adap, u8 dev, uint addr,
int alen, u8 *data, int length)
{
struct lpc32xx_i2c_registers *i2c = lpc32xx_i2c[adap->hwadapnr];
int stat, wlen;
/* Soft-reset the controller */
writel(LPC32XX_I2C_SOFT_RESET, &i2c->ctrl);
while (readl(&i2c->ctrl) & LPC32XX_I2C_SOFT_RESET)
;
/* do we need to write an address at all? */
if (alen) {
/* Address slave in write mode */
writel((dev<<1) | LPC32XX_I2C_TX_START, &i2c->tx);
/* write address bytes */
while (alen--) {
/* compute address byte + stop for the last one */
int a = (addr >> (8 * alen)) & 0xff;
if (!alen)
a |= LPC32XX_I2C_TX_STOP;
/* Send address byte */
writel(a, &i2c->tx);
}
/* wait for end of transation */
while (!((stat = readl(&i2c->stat)) & LPC32XX_I2C_STAT_TDI))
;
/* clear end-of-transaction flag */
writel(1, &i2c->stat);
}
/* do we have to read data at all? */
if (length) {
/* Address slave in read mode */
writel(1 | (dev<<1) | LPC32XX_I2C_TX_START, &i2c->tx);
wlen = length;
/* get data */
while (length | wlen) {
/* read status for TFF and RFE */
stat = readl(&i2c->stat);
/* must we, can we write a trigger byte? */
if ((wlen > 0)
& (!(stat & LPC32XX_I2C_STAT_TFF))) {
wlen--;
/* write trigger byte + stop if last */
writel(wlen ? 0 :
LPC32XX_I2C_TX_STOP, &i2c->tx);
}
/* must we, can we read a data byte? */
if ((length > 0)
& (!(stat & LPC32XX_I2C_STAT_RFE))) {
length--;
/* read byte */
*(data++) = readl(&i2c->rx);
}
}
/* wait for end of transation */
while (!((stat = readl(&i2c->stat)) & LPC32XX_I2C_STAT_TDI))
;
/* clear end-of-transaction flag */
writel(1, &i2c->stat);
}
/* success */
return 0;
}
/*
* I2C write called by cmd_i2c when doing 'i2c write' and by cmd_eeprom.c
* Begin write, send address byte(s), send data bytes, end.
*/
static int lpc32xx_i2c_write(struct i2c_adapter *adap, u8 dev, uint addr,
int alen, u8 *data, int length)
{
struct lpc32xx_i2c_registers *i2c = lpc32xx_i2c[adap->hwadapnr];
int stat;
/* Soft-reset the controller */
writel(LPC32XX_I2C_SOFT_RESET, &i2c->ctrl);
while (readl(&i2c->ctrl) & LPC32XX_I2C_SOFT_RESET)
;
/* do we need to write anything at all? */
if (alen | length)
/* Address slave in write mode */
writel((dev<<1) | LPC32XX_I2C_TX_START, &i2c->tx);
else
return 0;
/* write address bytes */
while (alen) {
/* wait for transmit fifo not full */
stat = readl(&i2c->stat);
if (!(stat & LPC32XX_I2C_STAT_TFF)) {
alen--;
int a = (addr >> (8 * alen)) & 0xff;
if (!(alen | length))
a |= LPC32XX_I2C_TX_STOP;
/* Send address byte */
writel(a, &i2c->tx);
}
}
while (length) {
/* wait for transmit fifo not full */
stat = readl(&i2c->stat);
if (!(stat & LPC32XX_I2C_STAT_TFF)) {
/* compute data byte, add stop if length==0 */
length--;
int d = *(data++);
if (!length)
d |= LPC32XX_I2C_TX_STOP;
/* Send data byte */
writel(d, &i2c->tx);
}
}
/* wait for end of transation */
while (!((stat = readl(&i2c->stat)) & LPC32XX_I2C_STAT_TDI))
;
/* clear end-of-transaction flag */
writel(1, &i2c->stat);
return 0;
}
U_BOOT_I2C_ADAP_COMPLETE(lpc32xx_0, _i2c_init, lpc32xx_i2c_probe,
lpc32xx_i2c_read, lpc32xx_i2c_write,
lpc32xx_i2c_set_bus_speed,
CONFIG_SYS_I2C_LPC32XX_SPEED,
CONFIG_SYS_I2C_LPC32XX_SLAVE,
0)
U_BOOT_I2C_ADAP_COMPLETE(lpc32xx_1, _i2c_init, lpc32xx_i2c_probe,
lpc32xx_i2c_read, lpc32xx_i2c_write,
lpc32xx_i2c_set_bus_speed,
CONFIG_SYS_I2C_LPC32XX_SPEED,
CONFIG_SYS_I2C_LPC32XX_SLAVE,
1)
U_BOOT_I2C_ADAP_COMPLETE(lpc32xx_2, _i2c_init, NULL,
lpc32xx_i2c_read, lpc32xx_i2c_write,
lpc32xx_i2c_set_bus_speed,
100000,
0,
2)
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