On 31.03.17 at 17:42, <swapnil.paratey@xxxxxxx> wrote:
The title needs improvement - it doesn't really reflect what the
patch does.
Add name=value parsing options for com1 and com2 to add flexibility
in setting register values for MMIO UART devices.
Maintain backward compatibility with previous positional parameter
specfications.
eg. com1=115200,8n1,0x3f8,4
eg. com1=baud=115200,parity=n,reg_width=4,reg_shift=2,irq=4
eg. com1=115200,8n1,0x3f8,4,reg_width=4,reg_shift=2
I would have been nice if you split the new format handling from
the addition of the new sub-options.
--- a/docs/misc/xen-command-line.markdown
+++ b/docs/misc/xen-command-line.markdown
@@ -324,6 +324,43 @@ Both option `com1` and `com2` follow the same format.
A typical setup for most situations might be `com1=115200,8n1`
+In addition to the above positional specification for UART parameters,
+name=value pair specfications are also supported. This is used to add
+flexibility for UART devices which require additional UART parameter
+configurations.
+
+The comma separation still delineates positional parameters. Hence,
+unless the parameter is explicitly specified with name=value option, it
+will be considered a positional parameter.
+
+The syntax consists of
+com1=(comma-separated positional parameters),(comma separated name-value pairs)
+
+The accepted name keywords for name=value pairs are
+ * `baud` - accepts integer baud rate (eg. 115200) or `auto`
+ * `bridge`- accepts xx:xx:xx. Similar to bridge-bdf in positional parameters.
+ notation is <bus>:<device>:<function>
+ * `clock_hz`- accepts large integers to setup UART clock frequencies.
+ Do note - these values are multiplied by 16.
+ * `data_bits` - integer between 5 and 8
+ * `dev` - accepted values are `pci` OR `amt`. If this option
+ is used to specify if the serial device is pci-based. The io_base
+ cannot be specified when `dev=pci` or `dev=amt` is used.
+ * `io_base` - accepts integer which specified IO base port for UART registers
+ * `irq` - IRQ number to use
+ * `parity` - accepted values are same as positional parameters
+ * `port` - used to specify which port the PCI serial device is located on
+ notation is xx:xx:xx <bus>:<device>:<function>
Everywhere above PCI device specifications wrongly use : instead
of . as separator between device and function.
+ * `reg_shift` - register shifts required to set UART registers
+ * `reg_width` - register width required to set UART registers
+ (only accepts 1 and 4)
+ * `stop_bits` - only accepts 1 or 2 for the number of stop bits
Since these are all new anyway, can we please use - instead of _
as separator characters inside sub-option names? Dashed are
slightly easier to type than underscores on most keyboards.
--- a/xen/common/kernel.c
+++ b/xen/common/kernel.c
@@ -48,7 +48,7 @@ static void __init assign_integer_param(
void __init cmdline_parse(const char *cmdline)
{
- char opt[100], *optval, *optkey, *q;
+ char opt[512], *optval, *optkey, *q;
Why not MAX_CMDLINE_LENGTH? But anyway both this and ...
--- a/xen/drivers/char/ns16550.c
+++ b/xen/drivers/char/ns16550.c
@@ -38,11 +38,27 @@
* can be specified in place of a numeric baud rate. Polled mode is specified
* by requesting irq 0.
*/
-static char __initdata opt_com1[30] = "";
-static char __initdata opt_com2[30] = "";
+static char __initdata opt_com1[MAX_CMDLINE_LENGTH] = "";
+static char __initdata opt_com2[MAX_CMDLINE_LENGTH] = "";
... this seems to be excessive growth.
+typedef enum e_serial_param_type {
+ BAUD=0,
Stray "=0". Also I don't think enumerator identifiers should be all
capitals.
+ BRIDGEBDF,
+ CLOCKHZ,
+ DATABITS,
+ DEVICE,
+ IO_BASE,
+ IRQ,
+ PARITY,
+ PORTBDF,
+ REG_SHIFT,
+ REG_WIDTH,
+ STOPBITS,
+ __MAX_SERIAL_PARAM /* introduce more parameters before this line */
Stray double underscores.
@@ -77,6 +93,29 @@ static struct ns16550 {
#endif
} ns16550_com[2] = { { 0 } };
+struct serial_param_var
+{
+ char *sp_name;
const
+ serial_param_type sp_type;
+};
+
+/* enum struct keeping a table of all accepted parameter names
+ * for parsing cmdline for serial port com1 and com2 */
+static struct serial_param_var sp_vars[] = {
const ... __initconst plus you should aim at arranging for the
string literals below to also get placed in .init.rodata (instead of
.rodata).
@@ -1083,26 +1122,70 @@ pci_uart_config(struct ns16550 *uart, bool_t skip_amt,
unsigned int idx)
}
#endif
+/* used to parse name value pairs and return which value it is
+ * along with pointer for the extracted value - ext_value */
+static serial_param_type get_token_value(char *token, char *ext_value)
__init
And the name is misleading - you obtain a token type and value.
Perhaps match_token() or get_token()?
+{
+ char *param_name;
const
+ int i;
unsigned int
+
+ param_name = strsep(&token, "=");
+ if ( param_name == NULL )
+ return __MAX_SERIAL_PARAM;
+ /* token has the param value after the equal to sign */
+ strlcpy(ext_value, token, MAX_PARAM_VALUE_LENGTH);
I think you'd better copy only once you found a match in the
table. And the size restriction would better be reflected in the
respective function parameter type (using ARRAY_SIZE() here).
+ /* linear search for the parameter */
+ for ( i = 0; i < ARRAY_SIZE(sp_vars); i++ )
+ {
+ if ( strcmp(sp_vars[i].sp_name, param_name) == 0 )
+ return sp_vars[i].sp_type;
+ }
+
+ return __MAX_SERIAL_PARAM;
+}
+
#define PARSE_ERR(_f, _a...) \
do { \
printk( "ERROR: " _f "\n" , ## _a ); \
return; \
} while ( 0 )
-static void __init ns16550_parse_port_config(
- struct ns16550 *uart, const char *conf)
+#define PARSE_ERR_RET(_f, _a...) \
+ do { \
+ printk( "ERROR: " _f "\n" , ## _a ); \
+ return 1; \
+ } while ( 0 )
+
+
+int parse_positional(struct ns16550 *uart, char **str)
static ... __init
Why is the return type of this function not void? All return
statements uniformly return zero.
{
int baud;
+ const char *conf;
+ char *name_val_pos;
- /* No user-specified configuration? */
- if ( (conf == NULL) || (*conf == '\0') )
+ conf = (const char *)*str;
Pointless cast.
+ name_val_pos = strchr(*str, '=');
Why don't you use conf here?
+
+ /* finding the end of the positional parameters */
+ if (name_val_pos)
{
- /* Some platforms may automatically probe the UART configuartion. */
- if ( uart->baud != 0 )
- goto config_parsed;
- return;
+ while (name_val_pos > *str)
+ {
+ name_val_pos--; /* working backwards from the = sign */
+ if (*name_val_pos == ',')
+ {
+ *name_val_pos = '\0';
+ name_val_pos++;
+ break;
+ }
+ }
}
+ *str = name_val_pos;
+ if (conf == *str) return 0; /* when there are no positional parameters */
Coding style for all the control statements above (more further down).
Also the return statement here goes on its own line.
@@ -1165,11 +1248,122 @@ static void __init ns16550_parse_port_config(
{
if ( !parse_pci(conf, NULL, &uart->pb_bdf[0],
&uart->pb_bdf[1], &uart->pb_bdf[2]) )
- PARSE_ERR("Bad bridge PCI coordinates");
+ PARSE_ERR_RET("Bad bridge PCI coordinates");
uart->pb_bdf_enable = 1;
}
#endif
+ return 0;
+}
+
+int parse_namevalue_pairs(char *str, struct ns16550 *uart)
static ... __init
Looking at the return values, this perhaps would better return bool.
+{
+ serial_param_type parsed_param;
+ char *token, *start;
+ char param_value[MAX_PARAM_VALUE_LENGTH];
+ bool dev_set;
+
+ dev_set = 0;
false (and true below)
+ start = str;
Please make both of these the initializers of the respective variables.
+ while (start != NULL) /* strsep gives NULL when there are no tokens found
*/
You didn't call strsep() yet when you first come here, so perhaps this
would better be do ... while ()?
+ {
+ /* when no tokens are found, start will be NULL */
+ token = strsep(&start, ",");
+
+ parsed_param = get_token_value(token, param_value);
+ switch(parsed_param)
I don't see the need for the intermediate variable here.
+ {
+ case BAUD:
case labels indent the same as the opening brace.
+ uart->baud = simple_strtoul(param_value, NULL, 0);
+ break;
+ case BRIDGEBDF:
+ if ( !parse_pci(param_value, NULL, &uart->ps_bdf[0],
+ &uart->ps_bdf[1], &uart->ps_bdf[2]))
Indentation.
+ PARSE_ERR_RET("Bad port PCI coordinates\n");
+ uart->ps_bdf_enable = 1;
true
+ break;
+ case CLOCKHZ:
+ uart->clock_hz = (simple_strtoul(param_value, NULL, 0) << 4);
+ break;
+ case DEVICE:
+ if ((strncmp(param_value, "pci", 3) == 0))
Stray pair of parentheses.
+ {
+ pci_uart_config(uart, 1/* skip AMT */, uart - ns16550_com);
+ dev_set = 1;
+ }
+ else if (strncmp(param_value, "amt", 3) == 0)
+ {
+ pci_uart_config(uart, 0, uart - ns16550_com);
+ dev_set = 1;
+ }
+ break;
+ case IO_BASE:
+ if (dev_set == 1)
+ PARSE_ERR_RET("Can't use io_base with dev=pci or dev=amt
options\n");
Doesn't this apply the other way around then too?
+ uart->io_base = simple_strtoul(param_value, NULL, 0);
+ break;
+ case IRQ:
+ uart->irq = simple_strtoul(param_value, NULL, 0);
+ break;
+ case DATABITS:
+ uart->data_bits = simple_strtoul(param_value, NULL, 0);
+ break;
+ case PARITY:
+ uart->parity = parse_parity_char(*param_value);
+ break;
+ case PORTBDF:
+ if ( !parse_pci(param_value, NULL, &uart->pb_bdf[0],
+ &uart->pb_bdf[1], &uart->pb_bdf[2]))
+ PARSE_ERR_RET("Bad port PCI coordinates\n");
+ uart->pb_bdf_enable = 1;
+ break;
+ case STOPBITS:
+ uart->stop_bits = simple_strtoul(param_value, NULL, 0);
+ break;
+ case REG_WIDTH:
+ uart->reg_width = simple_strtoul(param_value, NULL, 0);
+ break;
+ case REG_SHIFT:
+ uart->reg_shift = simple_strtoul(param_value, NULL, 0);
+ break;
+ default:
+ printk("Invalid parameter: %s\n", token);
PARSE_ERR_RET()?
+static void __init ns16550_parse_port_config(
+ struct ns16550 *uart, const char *conf)
+{
+ char cmdline[MAX_CMDLINE_LENGTH];
This isn't the entire cmdline, is it?
+ char *str;
+
+ /* No user-specified configuration? */
+ if ( (conf == NULL) || (*conf == '\0') )
+ {
+ /* Some platforms may automatically probe the UART configuartion. */
+ if ( uart->baud != 0 )
+ goto config_parsed;
+ return;
+ }
+
+ strlcpy(cmdline, conf, MAX_CMDLINE_LENGTH);
+ str = cmdline; /* good idea to use another pointer and keep cmdline alone
*/
Because of? Also comment style (not just here).
+ /* parse positional parameters and get pointer for name-value pairs */
+ if ( parse_positional(uart, &str) )
+ return;
+
+ if ( (str == NULL) || (*str == '\0') )
+ goto config_parsed;
+
+ if ( parse_namevalue_pairs(str, uart) )
+ return;
+
config_parsed:
Please avoid goto outside of error cleanup path where they're not
really making code structure a lot better. The two if()s above can
be easily re-arranged to do so, and I think the other goto a few lines
up also wouldn't be difficult to eliminate.
@@ -1177,6 +1371,8 @@ static void __init ns16550_parse_port_config(
PARSE_ERR("Baud rate %d outside supported range.", uart->baud);
if ( (uart->data_bits < 5) || (uart->data_bits > 8) )
PARSE_ERR("%d data bits are unsupported.", uart->data_bits);
+ if ( (uart->reg_width != 1) && (uart->reg_width != 4) )
+ PARSE_ERR("red_width accepted values: 1 or 4.");
"reg_width ..."
Also please avoid the full stop.
--- a/xen/include/xen/serial.h
+++ b/xen/include/xen/serial.h
@@ -20,6 +20,8 @@ void serial_set_rx_handler(int handle, serial_rx_fn fn);
/* Number of characters we buffer for a polling receiver. */
#define serial_rxbufsz 32
+#define MAX_CMDLINE_LENGTH 512
+#define MAX_PARAM_VALUE_LENGTH 16
Please don't put constants needed in only a single source file into
a header, even less so with such generic names.
Jan
