[patch v4 2/3] staging: speakup: check and convert dev name or ser to dev_t

[Okash Khawaja <okash.khawaja@gmail.com>]

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This patch adds functionality to validate and convert either a device
name or 'ser' memmber of synth into dev_t. Subsequent patch in this set
will call it to convert user-specified device into device number. For
device name, this patch does some basic sanity checks on the string
passed in. It currently supports ttyS*, ttyUSB* and, for selected
synths, lp*.

The patch also introduces a string member variable named 'dev_name' to
struct spk_synth. 'dev_name' represents the device name - ttyUSB0 etc -
which needs conversion to dev_t.

Signed-off-by: Okash Khawaja <okash.khawaja@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>

---
 drivers/staging/speakup/spk_priv.h  |    2 +
 drivers/staging/speakup/spk_ttyio.c |   42 ++++++++++++++++++++++++++++++++++++
 drivers/staging/speakup/spk_types.h |    1 
 3 files changed, 45 insertions(+)

--- a/drivers/staging/speakup/spk_priv.h
+++ b/drivers/staging/speakup/spk_priv.h
@@ -40,6 +40,8 @@
 
 #define KT_SPKUP 15
 #define SPK_SYNTH_TIMEOUT 100000 /* in micro-seconds */
+#define SYNTH_DEFAULT_DEV "ttyS0"
+#define SYNTH_DEFAULT_SER 0
 
 const struct old_serial_port *spk_serial_init(int index);
 void spk_stop_serial_interrupt(void);
--- a/drivers/staging/speakup/spk_ttyio.c
+++ b/drivers/staging/speakup/spk_ttyio.c
@@ -7,6 +7,11 @@
 #include "spk_types.h"
 #include "spk_priv.h"
 
+#define DEV_PREFIX_LP "lp"
+
+static const char * const lp_supported[] = { "acntsa", "bns", "dummy",
+	"txprt" };
+
 struct spk_ldisc_data {
 	char buf;
 	struct semaphore sem;
@@ -16,6 +21,43 @@ struct spk_ldisc_data {
 static struct spk_synth *spk_ttyio_synth;
 static struct tty_struct *speakup_tty;
 
+int ser_to_dev(int ser, dev_t *dev_no)
+{
+	if (ser < 0 || ser > (255 - 64)) {
+		pr_err("speakup: Invalid ser param. Must be between 0 and 191 inclusive.\n");
+		return -EINVAL;
+	}
+
+	*dev_no = MKDEV(4, (64 + ser));
+	return 0;
+}
+
+static int get_dev_to_use(struct spk_synth *synth, dev_t *dev_no)
+{
+	/* use ser only when dev is not specified */
+	if (strcmp(synth->dev_name, SYNTH_DEFAULT_DEV) ||
+	    synth->ser == SYNTH_DEFAULT_SER) {
+		/* for /dev/lp* check if synth is supported */
+		if (strncmp(synth->dev_name, DEV_PREFIX_LP,
+		    strlen(DEV_PREFIX_LP)) == 0)
+			if (match_string(lp_supported, ARRAY_SIZE(lp_supported),
+			    synth->name) < 0)  {
+				int i;
+
+				pr_err("speakup: lp* is only supported on:");
+				for (i = 0; i < ARRAY_SIZE(lp_supported); i++)
+					pr_cont(" %s", lp_supported[i]);
+				pr_cont("\n");
+
+				return -ENOTSUPP;
+			}
+
+		return tty_dev_name_to_number(synth->dev_name, dev_no);
+	}
+
+	return ser_to_dev(synth->ser, dev_no);
+}
+
 static int spk_ttyio_ldisc_open(struct tty_struct *tty)
 {
 	struct spk_ldisc_data *ldisc_data;
--- a/drivers/staging/speakup/spk_types.h
+++ b/drivers/staging/speakup/spk_types.h
@@ -169,6 +169,7 @@ struct spk_synth {
 	int jiffies;
 	int full;
 	int ser;
+	char *dev_name;
 	short flags;
 	short startup;
 	const int checkval; /* for validating a proper synth module */