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serial: support defining number of stop bits in serial URI
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in the past the serial backend was limited to a single stop bit, when
most hardware can support one or two. This allows URIs to define the
number of stop bits in a standard notation (8n1). This means serial uri
are now defined as:

serial:port,baud,config
serial:/dev/ttyUSB0,115200,8n1

This does break backwards compatibility with the previous serial URI
which was:

serial:/dev/ttyUSB0,115200n8

Since this is outside the library, and there are few serial users, and
8n1 is the "standard" way of doing things - it's better to change/update
now.

Update the doc (which mistakenly said we supported this).

Signed-off-by: Robin Getz <[email protected]>
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rgetz committed May 15, 2020
1 parent 6fc25d5 commit aeedb21
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Showing 2 changed files with 90 additions and 28 deletions.
18 changes: 12 additions & 6 deletions iio.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -411,14 +411,20 @@ __api __check_ret struct iio_context * iio_create_network_context(const char *ho
* - Network backend, "ip:"\n Requires a hostname, IPv4, or IPv6 to connect to
* a specific running IIO Daemon or no address part for automatic discovery
* when library is compiled with ZeroConf support. For example
* <i>"ip:192.168.2.1"</i>, <i>"ip:localhost"</i>, <i>"ip:"</i>
* <i>"ip:192.168.2.1"</i>, <b>or</b> <i>"ip:localhost"</i>, <b>or</b> <i>"ip:"</i>
* <b>or</b> <i>"ip:plutosdr.local"</i>
* - USB backend, "usb:"\n Requires bus, address, and interface parts separated
* with a dot. For example <i>"usb:3.32.5"</i>
* - Serial backend, "serial:"\n Requires a port, baud_rate, parity ('<b>n</b>'
* none, 'o' odd, 'e' even, 'm' mark, 's' space), bits (<b>8</b>), and flow
* ('<b>\0</b>' none, 'x' Xon Xoff, 'r' RTSCTS, 'd' DTRDSR) parts separated
* with a comma. For example <i>"serial:/dev/ttyUSB0,115200"</i>,
* <i>"serial:/dev/ttyUSB0,115200,n,8,1"</i>*/
* - Serial backend, "serial:"\n Requires:
* - a port (/dev/ttyUSB0),
* - baud_rate (default <b>115200</b>)
* - serial port configuration
* - data bits (5 6 7 <b>8</b> 9)
* - parity ('<b>n</b>' none, 'o' odd, 'e' even, 'm' mark, 's' space)
* - stop bits (<b>1</b> 2)
* - flow control ('<b>\0</b>' none, 'x' Xon Xoff, 'r' RTSCTS, 'd' DTRDSR)
*
* For example <i>"serial:/dev/ttyUSB0,115200"</i> <b>or</b> <i>"serial:/dev/ttyUSB0,115200,8n1"</i>*/
__api __check_ret struct iio_context * iio_create_context_from_uri(const char *uri);


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100 changes: 78 additions & 22 deletions serial.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -314,7 +314,7 @@ static int apply_settings(struct sp_port *port, unsigned int baud_rate,
}

static struct iio_context * serial_create_context(const char *port_name,
unsigned int baud_rate, unsigned int bits,
unsigned int baud_rate, unsigned int bits, unsigned int stop,
enum sp_parity parity, enum sp_flowcontrol flow)
{
struct sp_port *port;
Expand All @@ -337,7 +337,7 @@ static struct iio_context * serial_create_context(const char *port_name,
goto err_free_port;
}

ret = apply_settings(port, baud_rate, bits, 1, parity, flow);
ret = apply_settings(port, baud_rate, bits, stop, parity, flow);
if (ret) {
errno = -ret;
goto err_close_port;
Expand Down Expand Up @@ -419,22 +419,66 @@ static struct iio_context * serial_create_context(const char *port_name,
return NULL;
}

/* Take string, in "[baud rate],[data bits][parity][stop bits][flow control]"
* notation, where:
* - baud_rate = between 110 - 1,000,000 (default 115200)
* - data bits = between 5 and 9 (default 8)
* - parity = one of 'n' none, 'o' odd, 'e' even, 'm' mark, 's' space
* (default 'n' none)
* - stop bits = 1 or 2 (default 1)
* - flow control = one of '\0' none, 'x' Xon Xoff, 'r' RTSCTS, 'd' DTRDSR
* (default '\0' none)
*
* eg: "115200,8n1x"
* "115200,8n1"
* "115200,8"
* "115200"
* ""
*/
static int serial_parse_params(const char *params,
unsigned int *baud_rate, unsigned int *bits,
unsigned int *baud_rate, unsigned int *bits, unsigned int *stop,
enum sp_parity *parity, enum sp_flowcontrol *flow)
{
char *end;

/* Default settings */
*baud_rate = 115200;
*parity = SP_PARITY_NONE;
*bits = 8;
*stop = 1;
*flow = SP_FLOWCONTROL_NONE;

if (!params || !params[0])
return 0;

*baud_rate = strtoul(params, &end, 10);
if (params == end)
return -EINVAL;

/* 110 baud to 1,000,000 baud */
if (*baud_rate < 110 || *baud_rate > 1000001)
return -EINVAL;

if (*end == ',')
end++;

if (!*end)
return 0;

params = (const char *)(end);

*bits = strtoul(params, &end, 10);
if (params == end)
return -EINVAL;

if (*bits > 9 || *bits < 5)
return -EINVAL;

if (*end == ',')
end++;

switch (*end) {
case '\0':
/* Default settings */
*bits = 8;
*parity = SP_PARITY_NONE;
*flow = SP_FLOWCONTROL_NONE;
return 0;
case 'n':
*parity = SP_PARITY_NONE;
Expand All @@ -455,21 +499,31 @@ static int serial_parse_params(const char *params,
return -EINVAL;
}

params = (const char *)((uintptr_t) end + 1);
end++;
if (*end == ',')
end++;

params = (const char *)(end);

if (!*params) {
*bits = 8;
*flow = SP_FLOWCONTROL_NONE;
if (!*params)
return 0;
}

*bits = strtoul(params, &end, 10);
params = (const char *)(end);
if (!*params)
return 0;
*stop = strtoul(params, &end, 10);

if (params == end)
return -EINVAL;

if (!*stop || *stop > 2)
return -EINVAL;

if (*end == ',')
end++;

switch (*end) {
case '\0':
*flow = SP_FLOWCONTROL_NONE;
return 0;
case 'x':
*flow = SP_FLOWCONTROL_XONXOFF;
Expand All @@ -495,7 +549,7 @@ struct iio_context * serial_create_context_from_uri(const char *uri)
{
struct iio_context *ctx = NULL;
char *comma, *uri_dup;
unsigned int baud_rate, bits;
unsigned int baud_rate, bits, stop;
enum sp_parity parity;
enum sp_flowcontrol flow;
int ret;
Expand All @@ -511,17 +565,19 @@ struct iio_context * serial_create_context_from_uri(const char *uri)
}

comma = strchr(uri_dup, ',');
if (!comma)
goto err_free_dup;

*comma = '\0';
if (comma) {
*comma = '\0';
ret = serial_parse_params((char *)((uintptr_t) comma + 1),
&baud_rate, &bits, &stop, &parity, &flow);
} else {
ret = serial_parse_params(NULL,
&baud_rate, &bits, &stop, &parity, &flow);
}

ret = serial_parse_params((char *)((uintptr_t) comma + 1),
&baud_rate, &bits, &parity, &flow);
if (ret)
goto err_free_dup;

ctx = serial_create_context(uri_dup, baud_rate, bits, parity, flow);
ctx = serial_create_context(uri_dup, baud_rate, bits, stop, parity, flow);

free(uri_dup);
return ctx;
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