The function converts strings like ttyS0 and ttyUSB0 to dev_t like
(4, 64) and (188, 0). Subsequent patch in this set will call it to
convert user-supplied device into device number. The function does
some basic sanity checks on the string passed in. It currently supports
ttyS*, ttyUSB* and, for selected synths, lp*.

In order to do this, the patch also introduces a string member variable
named 'dev' to struct spk_synth. 'dev' represents the device name -
ttyUSB0 etc - which needs conversion to dev_t.

Signed-off-by: Okash Khawaja <okash.khawaja@gmail.com>
Reviewed-by: Samuel Thibault <samuel.thibault@ens-lyon.org>

---
 drivers/staging/speakup/spk_priv.h  |    2 
 drivers/staging/speakup/spk_ttyio.c |  105 ++++++++++++++++++++++++++++++++++++
 drivers/staging/speakup/spk_types.h |    1 
 3 files changed, 108 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 +7,13 @@
 #include "spk_types.h"
 #include "spk_priv.h"
 
+/* Supported device types */
+#define DEV_PREFIX_TTYS "ttyS"
+#define DEV_PREFIX_TTYUSB "ttyUSB"
+#define DEV_PREFIX_LP "lp"
+
+const char *lp_supported[] = { "acntsa", "bns", "dummy", "txprt" };
+
 struct spk_ldisc_data {
 	char buf;
 	struct semaphore sem;
@@ -16,6 +23,104 @@ struct spk_ldisc_data {
 static struct spk_synth *spk_ttyio_synth;
 static struct tty_struct *speakup_tty;
 
+static int name_to_dev(const char *name, dev_t *dev_no)
+{
+        int maj = -1, min = -1;
+
+        if (strncmp(name, DEV_PREFIX_TTYS, strlen(DEV_PREFIX_TTYS)) == 0) {
+                if (kstrtoint(name + strlen(DEV_PREFIX_TTYS), 10, &min)) {
+			pr_err("speakup: Invalid ser param. Must be \
+					between 0 and 191 inclusive.\n");
+                        return -EINVAL;
+                }
+                maj = 4;
+
+                if (min < 0 || min > 191) {
+			pr_err("speakup: Invalid ser param. Must be \
+					between 0 and 191 inclusive.\n");
+                        return -EINVAL;
+                }
+                min = min + 64;
+        } else if (strncmp(name, DEV_PREFIX_TTYUSB, strlen(DEV_PREFIX_TTYUSB))
+			== 0) {
+                if (kstrtoint(name + strlen(DEV_PREFIX_TTYUSB), 10, &min)) {
+                        pr_err("speakup: Invalid ttyUSB number. \
+					Must be a number from 0 onwards\n");
+                        return -EINVAL;
+                }
+                maj = 188;
+
+                if (min < 0) {
+                        pr_err("speakup: Invalid ttyUSB number. \
+					Must be a number from 0 onwards\n");
+                        return -EINVAL;
+                }
+        } else if (strncmp(name, DEV_PREFIX_LP, strlen(DEV_PREFIX_LP)) == 0) {
+                if (kstrtoint(name + strlen(DEV_PREFIX_LP), 10, &min)) {
+                        pr_warn("speakup: Invalid lp number. \
+					Must be a number from 0 onwards\n");
+                        return -EINVAL;
+                }
+                maj = 6;
+
+                if (min < 0) {
+                        pr_warn("speakup: Invalid lp number. \
+					Must be a number from 0 onwards\n");
+                        return -EINVAL;
+                }
+        }
+
+        if (maj == -1 || min == -1)
+                return -EINVAL;
+
+        /* if here, maj and min must be valid */
+        *dev_no = MKDEV(maj, min);
+
+        return 0;
+}
+
+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, SYNTH_DEFAULT_DEV) || synth->ser == SYNTH_DEFAULT_SER) {
+		/* for /dev/lp* check if synth is supported */
+		if (strncmp(synth->dev, DEV_PREFIX_LP, strlen(DEV_PREFIX_LP)) == 0) {
+			int i;
+
+			for (i = 0; i < ARRAY_SIZE(lp_supported); i++) {
+				if (strcmp(synth->name, lp_supported[i]) == 0)
+					break;
+			}
+
+			if (i >= ARRAY_SIZE(lp_supported)) {
+				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 name_to_dev(synth->dev, 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;
 	short flags;
 	short startup;
 	const int checkval; /* for validating a proper synth module */