GitHub-Mirror/u-boot
2
0
Fork 0
mirror of https://github.com/Fishwaldo/u-boot.git synced 2025-03-22 07:01:39 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

i2c: mvtwsi: Improve and fix comments

Browse source 
This patch fixes only comments/documentation: Streamline capitalization
and improve grammar/punctuation.

Signed-off-by: Mario Six <mario.six@gdsys.cc>
Reviewed-by: Stefan Roese <sr@denx.de>
This commit is contained in:
mario.six@gdsys.cc 2016-07-21 11:57:03 +02:00 • committed by Heiko Schocher
parent dfc3958cd3
commit 49c801bf35
1 changed files with 62 additions and 67 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

129
drivers/i2c/mvtwsi.c
View file

@ -14,8 +14,8 @@
#include <asm/io.h> #include <asm/io.h>
/* /*
* include a file that will provide CONFIG_I2C_MVTWSI_BASE* * Include a file that will provide CONFIG_I2C_MVTWSI_BASE*, and possibly other
* and possibly other settings * settings
*/ */
#if defined(CONFIG_ORION5X) #if defined(CONFIG_ORION5X)
@ -51,8 +51,8 @@ struct mvtwsi_registers {
u32 data; u32 data;
u32 control; u32 control;
union { union {
u32 status; /* when reading */ u32 status; /* When reading */
u32 baudrate; /* when writing */ u32 baudrate; /* When writing */
}; };
u32 xtnd_slave_addr; u32 xtnd_slave_addr;
u32 reserved[2]; u32 reserved[2];
@ -81,8 +81,8 @@ enum mvtwsi_ctrl_register_fields {
}; };
/* /*
* On sun6i and newer IFLG is a write-clear bit which is cleared by writing 1, * On sun6i and newer, IFLG is a write-clear bit, which is cleared by writing 1;
* on other platforms it is a normal r/w bit which is cleared by writing 0. * on other platforms, it is a normal r/w bit, which is cleared by writing 0.
*/ */
#ifdef CONFIG_SUNXI_GEN_SUN6I #ifdef CONFIG_SUNXI_GEN_SUN6I
@ -194,8 +194,8 @@ inline uint mvtwsi_error(uint ec, uint lc, uint ls, uint es)
} }
/* /*
* Wait for IFLG to raise, or return 'timeout'; then if status is as expected, * Wait for IFLG to raise, or return 'timeout.' Then, if the status is as
* return 0 (ok) or return 'wrong status'. * expected, return 0 (ok) or 'wrong status' otherwise.
*/ */
static int twsi_wait(struct i2c_adapter *adap, int expected_status) static int twsi_wait(struct i2c_adapter *adap, int expected_status)
{ {
@ -214,7 +214,7 @@ static int twsi_wait(struct i2c_adapter *adap, int expected_status)
MVTWSI_ERROR_WRONG_STATUS, MVTWSI_ERROR_WRONG_STATUS,
control, status, expected_status); control, status, expected_status);
} }
udelay(10); /* one clock cycle at 100 kHz */ udelay(10); /* One clock cycle at 100 kHz */
} while (timeout--); } while (timeout--);
status = readl(&twsi->status); status = readl(&twsi->status);
return mvtwsi_error(MVTWSI_ERROR_TIMEOUT, control, status, return mvtwsi_error(MVTWSI_ERROR_TIMEOUT, control, status,
@ -229,12 +229,12 @@ static int twsi_start(struct i2c_adapter *adap, int expected_status, u8 *flags)
{ {
struct mvtwsi_registers *twsi = twsi_get_base(adap); struct mvtwsi_registers *twsi = twsi_get_base(adap);
/* globally set TWSIEN in case it was not */ /* Set TWSIEN */
*flags |= MVTWSI_CONTROL_TWSIEN; *flags |= MVTWSI_CONTROL_TWSIEN;
/* assert START */ /* Assert START */
writel(*flags | MVTWSI_CONTROL_START | writel(*flags | MVTWSI_CONTROL_START |
MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control); MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control);
/* wait for controller to process START */ /* Wait for controller to process START */
return twsi_wait(adap, expected_status); return twsi_wait(adap, expected_status);
} }
@ -246,42 +246,40 @@ static int twsi_send(struct i2c_adapter *adap, u8 byte, int expected_status,
{ {
struct mvtwsi_registers *twsi = twsi_get_base(adap); struct mvtwsi_registers *twsi = twsi_get_base(adap);
/* put byte in data register for sending */ /* Write byte to data register for sending */
writel(byte, &twsi->data); writel(byte, &twsi->data);
/* clear any pending interrupt -- that'll cause sending */ /* Clear any pending interrupt -- that will cause sending */
writel(*flags | MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control); writel(*flags | MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control);
/* wait for controller to receive byte and check ACK */ /* Wait for controller to receive byte, and check ACK */
return twsi_wait(adap, expected_status); return twsi_wait(adap, expected_status);
} }
/* /*
* Receive a byte. * Receive a byte.
* Global mvtwsi_control_flags variable says if we should ack or nak.
*/ */
static int twsi_recv(struct i2c_adapter *adap, u8 *byte, u8 *flags) static int twsi_recv(struct i2c_adapter *adap, u8 *byte, u8 *flags)
{ {
struct mvtwsi_registers *twsi = twsi_get_base(adap); struct mvtwsi_registers *twsi = twsi_get_base(adap);
int expected_status, status; int expected_status, status;
/* compute expected status based on ACK bit in global control flags */ /* Compute expected status based on ACK bit in passed control flags */
if (*flags & MVTWSI_CONTROL_ACK) if (*flags & MVTWSI_CONTROL_ACK)
expected_status = MVTWSI_STATUS_DATA_R_ACK; expected_status = MVTWSI_STATUS_DATA_R_ACK;
else else
expected_status = MVTWSI_STATUS_DATA_R_NAK; expected_status = MVTWSI_STATUS_DATA_R_NAK;
/* acknowledge *previous state* and launch receive */ /* Acknowledge *previous state*, and launch receive */
writel(*flags | MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control); writel(*flags | MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control);
/* wait for controller to receive byte and assert ACK or NAK */ /* Wait for controller to receive byte, and assert ACK or NAK */
status = twsi_wait(adap, expected_status); status = twsi_wait(adap, expected_status);
/* if we did receive expected byte then store it */ /* If we did receive the expected byte, store it */
if (status == 0) if (status == 0)
*byte = readl(&twsi->data); *byte = readl(&twsi->data);
/* return status */
return status; return status;
} }
/* /*
* Assert the STOP condition. * Assert the STOP condition.
* This is also used to force the bus back in idle (SDA=SCL=1). * This is also used to force the bus back to idle (SDA = SCL = 1).
*/ */
static int twsi_stop(struct i2c_adapter *adap, int status) static int twsi_stop(struct i2c_adapter *adap, int status)
{ {
@ -289,15 +287,15 @@ static int twsi_stop(struct i2c_adapter *adap, int status)
int control, stop_status; int control, stop_status;
int timeout = 1000; int timeout = 1000;
/* assert STOP */ /* Assert STOP */
control = MVTWSI_CONTROL_TWSIEN | MVTWSI_CONTROL_STOP; control = MVTWSI_CONTROL_TWSIEN | MVTWSI_CONTROL_STOP;
writel(control | MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control); writel(control | MVTWSI_CONTROL_CLEAR_IFLG, &twsi->control);
/* wait for IDLE; IFLG won't rise so twsi_wait() is no use. */ /* Wait for IDLE; IFLG won't rise, so we can't use twsi_wait() */
do { do {
stop_status = readl(&twsi->status); stop_status = readl(&twsi->status);
if (stop_status == MVTWSI_STATUS_IDLE) if (stop_status == MVTWSI_STATUS_IDLE)
break; break;
udelay(10); /* one clock cycle at 100 kHz */ udelay(10); /* One clock cycle at 100 kHz */
} while (timeout--); } while (timeout--);
control = readl(&twsi->control); control = readl(&twsi->control);
if (stop_status != MVTWSI_STATUS_IDLE) if (stop_status != MVTWSI_STATUS_IDLE)
@ -326,26 +324,26 @@ static void twsi_reset(struct i2c_adapter *adap)
{ {
struct mvtwsi_registers *twsi = twsi_get_base(adap); struct mvtwsi_registers *twsi = twsi_get_base(adap);
/* reset controller */ /* Reset controller */
writel(0, &twsi->soft_reset); writel(0, &twsi->soft_reset);
/* wait 2 ms -- this is what the Marvell LSP does */ /* Wait 2 ms -- this is what the Marvell LSP does */
udelay(20000); udelay(20000);
} }
/* /*
* I2C init called by cmd_i2c when doing 'i2c reset'. * Sets baud to the highest possible value not exceeding the requested one.
* Sets baud to the highest possible value not exceeding requested one.
*/ */
static unsigned int twsi_i2c_set_bus_speed(struct i2c_adapter *adap, static unsigned int twsi_i2c_set_bus_speed(struct i2c_adapter *adap,
unsigned int requested_speed) unsigned int requested_speed)
{ {
struct mvtwsi_registers *twsi = twsi_get_base(adap); struct mvtwsi_registers *twsi = twsi_get_base(adap);
unsigned int tmp_speed, highest_speed, n, m; unsigned int tmp_speed, highest_speed, n, m;
unsigned int baud = 0x44; /* baudrate at controller reset */ unsigned int baud = 0x44; /* Baud rate after controller reset */
/* use actual speed to collect progressively higher values */
highest_speed = 0; highest_speed = 0;
/* compute m, n setting for highest speed not above requested speed */ /* Successively try m, n combinations, and use the combination
* resulting in the largest speed that's not above the requested
* speed */
for (n = 0; n < 8; n++) { for (n = 0; n < 8; n++) {
for (m = 0; m < 16; m++) { for (m = 0; m < 16; m++) {
tmp_speed = twsi_calc_freq(n, m); tmp_speed = twsi_calc_freq(n, m);
@ -364,20 +362,19 @@ static void twsi_i2c_init(struct i2c_adapter *adap, int speed, int slaveadd)
{ {
struct mvtwsi_registers *twsi = twsi_get_base(adap); struct mvtwsi_registers *twsi = twsi_get_base(adap);
/* reset controller */ /* Reset controller */
twsi_reset(adap); twsi_reset(adap);
/* set speed */ /* Set speed */
twsi_i2c_set_bus_speed(adap, speed); twsi_i2c_set_bus_speed(adap, speed);
/* set slave address even though we don't use it */ /* Set slave address; even though we don't use it */
writel(slaveadd, &twsi->slave_address); writel(slaveadd, &twsi->slave_address);
writel(0, &twsi->xtnd_slave_addr); writel(0, &twsi->xtnd_slave_addr);
/* assert STOP but don't care for the result */ /* Assert STOP, but don't care for the result */
(void) twsi_stop(adap, 0); (void) twsi_stop(adap, 0);
} }
/* /*
* Begin I2C transaction with expected start status, at given address. * Begin I2C transaction with expected start status, at given address.
* Common to i2c_probe, i2c_read and i2c_write.
* Expected address status will derive from direction bit (bit 0) in addr. * Expected address status will derive from direction bit (bit 0) in addr.
*/ */
static int i2c_begin(struct i2c_adapter *adap, int expected_start_status, static int i2c_begin(struct i2c_adapter *adap, int expected_start_status,
@ -385,23 +382,23 @@ static int i2c_begin(struct i2c_adapter *adap, int expected_start_status,
{ {
int status, expected_addr_status; int status, expected_addr_status;
/* compute expected address status from direction bit in addr */ /* Compute the expected address status from the direction bit in
if (addr & 1) /* reading */ * the address byte */
if (addr & 1) /* Reading */
expected_addr_status = MVTWSI_STATUS_ADDR_R_ACK; expected_addr_status = MVTWSI_STATUS_ADDR_R_ACK;
else /* writing */ else /* Writing */
expected_addr_status = MVTWSI_STATUS_ADDR_W_ACK; expected_addr_status = MVTWSI_STATUS_ADDR_W_ACK;
/* assert START */ /* Assert START */
status = twsi_start(adap, expected_start_status, flags); status = twsi_start(adap, expected_start_status, flags);
/* send out the address if the start went well */ /* Send out the address if the start went well */
if (status == 0) if (status == 0)
status = twsi_send(adap, addr, expected_addr_status, status = twsi_send(adap, addr, expected_addr_status,
flags); flags);
/* return ok or status of first failure to caller */ /* Return 0, or the status of the first failure */
return status; return status;
} }
/* /*
* I2C probe called by cmd_i2c when doing 'i2c probe'.
* Begin read, nak data byte, end. * Begin read, nak data byte, end.
*/ */
static int twsi_i2c_probe(struct i2c_adapter *adap, uchar chip) static int twsi_i2c_probe(struct i2c_adapter *adap, uchar chip)
@ -410,26 +407,24 @@ static int twsi_i2c_probe(struct i2c_adapter *adap, uchar chip)
u8 flags = 0; u8 flags = 0;
int status; int status;
/* begin i2c read */ /* Begin i2c read */
status = i2c_begin(adap, MVTWSI_STATUS_START, (chip << 1) | 1, &flags); status = i2c_begin(adap, MVTWSI_STATUS_START, (chip << 1) | 1, &flags);
/* dummy read was accepted: receive byte but NAK it. */ /* Dummy read was accepted: receive byte, but NAK it. */
if (status == 0) if (status == 0)
status = twsi_recv(adap, &dummy_byte, &flags); status = twsi_recv(adap, &dummy_byte, &flags);
/* Stop transaction */ /* Stop transaction */
twsi_stop(adap, 0); twsi_stop(adap, 0);
/* return 0 or status of first failure */ /* Return 0, or the status of the first failure */
return status; return status;
} }
/* /*
* 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. * Begin write, send address byte(s), begin read, receive data bytes, end.
* *
* NOTE: some EEPROMS want a stop right before the second start, while * NOTE: Some devices want a stop right before the second start, while some
* some will choke if it is there. Deciding which we should do is eeprom * will choke if it is there. Since deciding this is not yet supported in
* stuff, not i2c, but at the moment the APIs won't let us put it in * higher level APIs, we need to make a decision here, and for the moment that
* cmd_eeprom, so we have to choose here, and for the moment that'll be * will be a repeated start without a preceding stop.
* a repeated start without a preceding stop.
*/ */
static int twsi_i2c_read(struct i2c_adapter *adap, uchar chip, uint addr, static int twsi_i2c_read(struct i2c_adapter *adap, uchar chip, uint addr,
int alen, uchar *data, int length) int alen, uchar *data, int length)
@ -437,35 +432,34 @@ static int twsi_i2c_read(struct i2c_adapter *adap, uchar chip, uint addr,
int status; int status;
u8 flags = 0; u8 flags = 0;
/* begin i2c write to send the address bytes */ /* Begin i2c write to send the address bytes */
status = i2c_begin(adap, MVTWSI_STATUS_START, (chip << 1), &flags); status = i2c_begin(adap, MVTWSI_STATUS_START, (chip << 1), &flags);
/* send addr bytes */ /* Send address bytes */
while ((status == 0) && alen--) while ((status == 0) && alen--)
status = twsi_send(adap, addr >> (8*alen), status = twsi_send(adap, addr >> (8*alen),
MVTWSI_STATUS_DATA_W_ACK, &flags); MVTWSI_STATUS_DATA_W_ACK, &flags);
/* begin i2c read to receive eeprom data bytes */ /* Begin i2c read to receive data bytes */
if (status == 0) if (status == 0)
status = i2c_begin(adap, MVTWSI_STATUS_REPEATED_START, status = i2c_begin(adap, MVTWSI_STATUS_REPEATED_START,
(chip << 1) | 1, &flags); (chip << 1) | 1, &flags);
/* prepare ACK if at least one byte must be received */ /* Prepare ACK if at least one byte must be received */
if (length > 0) if (length > 0)
flags |= MVTWSI_CONTROL_ACK; flags |= MVTWSI_CONTROL_ACK;
/* now receive actual bytes */ /* Receive actual data bytes */
while ((status == 0) && length--) { while ((status == 0) && length--) {
/* reset NAK if we if no more to read now */ /* Set NAK if we if we have nothing more to read */
if (length == 0) if (length == 0)
flags &= ~MVTWSI_CONTROL_ACK; flags &= ~MVTWSI_CONTROL_ACK;
/* read current byte */ /* Read current byte */
status = twsi_recv(adap, data++, &flags); status = twsi_recv(adap, data++, &flags);
} }
/* Stop transaction */ /* Stop transaction */
status = twsi_stop(adap, status); status = twsi_stop(adap, status);
/* return 0 or status of first failure */ /* Return 0, or the status of the first failure */
return status; return status;
} }
/* /*
* 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. * Begin write, send address byte(s), send data bytes, end.
*/ */
static int twsi_i2c_write(struct i2c_adapter *adap, uchar chip, uint addr, static int twsi_i2c_write(struct i2c_adapter *adap, uchar chip, uint addr,
@ -474,19 +468,20 @@ static int twsi_i2c_write(struct i2c_adapter *adap, uchar chip, uint addr,
int status; int status;
u8 flags = 0; u8 flags = 0;
/* begin i2c write to send the eeprom adress bytes then data bytes */ /* Begin i2c write to send first the address bytes, then the
* data bytes */
status = i2c_begin(adap, MVTWSI_STATUS_START, (chip << 1), &flags); status = i2c_begin(adap, MVTWSI_STATUS_START, (chip << 1), &flags);
/* send addr bytes */ /* Send address bytes */
while ((status == 0) && alen--) while ((status == 0) && alen--)
status = twsi_send(adap, addr >> (8*alen), status = twsi_send(adap, addr >> (8*alen),
MVTWSI_STATUS_DATA_W_ACK, &flags); MVTWSI_STATUS_DATA_W_ACK, &flags);
/* send data bytes */ /* Send data bytes */
while ((status == 0) && (length-- > 0)) while ((status == 0) && (length-- > 0))
status = twsi_send(adap, *(data++), MVTWSI_STATUS_DATA_W_ACK, status = twsi_send(adap, *(data++), MVTWSI_STATUS_DATA_W_ACK,
&flags); &flags);
/* Stop transaction */ /* Stop transaction */
status = twsi_stop(adap, status); status = twsi_stop(adap, status);
/* return 0 or status of first failure */ /* Return 0, or the status of the first failure */
return status; return status;
} }