diff --git a/drivers/lcd/pcf8574_lcd_backpack.c b/drivers/lcd/pcf8574_lcd_backpack.c
index c06a0951dd8ececaabc45f64fec95c5b82e79c2a..a8e288c6cc372dab379bf8420432aab26b4503cc 100644
--- a/drivers/lcd/pcf8574_lcd_backpack.c
+++ b/drivers/lcd/pcf8574_lcd_backpack.c
@@ -86,6 +86,8 @@
# define lcdvdbg(x...)
#endif
+#define MAX_OPENCNT (255) /* Limit of uint8_t */
+
/****************************************************************************
* Private Types
****************************************************************************/
@@ -95,6 +97,8 @@ struct pcf8574_lcd_dev_s
FAR struct i2c_master_s *i2c; /* I2C interface */
struct pcf8574_lcd_backpack_config_s cfg; /* gpio configuration */
uint8_t bl_bit; /* current backlight bit */
+ uint8_t refs; /* Number of references */
+ uint8_t unlinked; /* We are unlinked, so teardown on last close */
sem_t sem_excl; /* mutex */
};
@@ -117,12 +121,16 @@ static ssize_t pcf8574_lcd_read(FAR struct file *filep, FAR char *buffer,
size_t buflen);
static ssize_t pcf8574_lcd_write(FAR struct file *filep,
FAR const char *buffer, size_t buflen);
+static off_t pcf8574_lcd_seek(FAR struct file *filep, off_t offset, int whence);
static int pcf8574_lcd_ioctl(FAR struct file *filep, int cmd,
unsigned long arg);
#ifndef CONFIG_DISABLE_POLL
static int pcf8574lcd_poll(FAR struct file *filep, FAR struct pollfd *fds,
bool setup);
#endif
+#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
+static int pcf8574_lcd_unlink(FAR struct inode *inode);
+#endif
/****************************************************************************
* Private Data
@@ -134,12 +142,14 @@ static const struct file_operations g_pcf8574_lcd_fops =
pcf8574_lcd_close, /* close */
pcf8574_lcd_read, /* read */
pcf8574_lcd_write, /* write */
- 0, /* seek */
+ pcf8574_lcd_seek, /* seek */
pcf8574_lcd_ioctl, /* ioctl */
#ifndef CONFIG_DISABLE_POLL
pcf8574lcd_poll, /* poll */
#endif
- 0 /* unlink */
+#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
+ pcf8574_lcd_unlink /* unlink */
+#endif
};
/****************************************************************************
@@ -1000,6 +1010,53 @@ static int lcd_getstream(FAR struct lib_instream_s *instream)
return EOF;
}
+/****************************************************************************
+ * Name: lcd_fpos_to_curpos
+ *
+ * Description:
+ * Convert a file logical offset to a screen cursor pos (row,col). This
+ * discounts 'synthesized' line feeds at the end of screen lines.
+ *
+ ****************************************************************************/
+
+static void lcd_fpos_to_curpos(FAR struct pcf8574_lcd_dev_s *priv,
+ off_t fpos, uint8_t *row, uint8_t *col, bool* onlf)
+{
+ int virtcols;
+
+ virtcols = (priv->cfg.cols + 1);
+
+ /* Determine if this is a 'virtual' position (on the synthetic LF) */
+
+ *onlf = (priv->cfg.cols == fpos % virtcols);
+
+ /* Adjust off any preceding synthetic LF's to get linear position */
+
+ fpos -= fpos / virtcols;
+
+ /* Compute row/col from linear position */
+
+ *row = fpos / priv->cfg.cols;
+ *col = fpos % priv->cfg.cols;
+}
+
+/****************************************************************************
+ * Name: lcd_curpos_to_fpos
+ *
+ * Description:
+ * Convert a screen cursor pos (row,col) to a file logical offset. This
+ * includes 'synthesized' line feeds at the end of screen lines.
+ *
+ ****************************************************************************/
+
+static void lcd_curpos_to_fpos(FAR struct pcf8574_lcd_dev_s *priv,
+ uint8_t row, uint8_t col, off_t* fpos)
+{
+ /* the logical file position is the linear position plus any synthetic LF */
+
+ *fpos = (row * priv->cfg.cols) + col + row;
+}
+
/****************************************************************************
* Name: pcf8574_lcd_open
*
@@ -1010,6 +1067,22 @@ static int lcd_getstream(FAR struct lib_instream_s *instream)
static int pcf8574_lcd_open(FAR struct file *filep)
{
+ FAR struct inode *inode = filep->f_inode;
+ FAR struct pcf8574_lcd_dev_s *priv = (FAR struct pcf8574_lcd_dev_s *)inode->i_private;
+
+ /* Increment the reference count */
+
+ sem_wait(&priv->sem_excl);
+ if (priv->refs == MAX_OPENCNT)
+ {
+ return -EMFILE;
+ }
+ else
+ {
+ priv->refs++;
+ }
+
+ sem_post(&priv->sem_excl);
return OK;
}
@@ -1023,7 +1096,35 @@ static int pcf8574_lcd_open(FAR struct file *filep)
static int pcf8574_lcd_close(FAR struct file *filep)
{
- return OK;
+ FAR struct inode *inode = filep->f_inode;
+ FAR struct pcf8574_lcd_dev_s *priv = (FAR struct pcf8574_lcd_dev_s *)inode->i_private;
+ int ret;
+
+ /* Decrement the reference count */
+
+ sem_wait(&priv->sem_excl);
+
+ if (priv->refs == 0)
+ {
+ ret = -EIO;
+ }
+ else
+ {
+ priv->refs--;
+
+ /* If we had previously unlinked, but there were open references at the
+ * time, we need to do the final teardown now.
+ */
+
+ if (priv->refs == 0 && priv->unlinked)
+ {
+ /* We have no real teardown at present */
+ }
+ ret = OK;
+ }
+
+ sem_post(&priv->sem_excl);
+ return ret;
}
/****************************************************************************
@@ -1031,7 +1132,8 @@ static int pcf8574_lcd_close(FAR struct file *filep)
*
* Description:
* This simply reads as much of the display memory as possible. This is
- * probably not very interesting.
+ * generally not very interesting, but we do it in a way that allows us to
+ * 'cat' the LCD contents via the shell.
*
****************************************************************************/
@@ -1044,22 +1146,44 @@ static ssize_t pcf8574_lcd_read(FAR struct file *filep, FAR char *buffer,
uint8_t addr;
uint8_t row;
uint8_t col;
+ bool onlf;
sem_wait(&priv->sem_excl);
/* Get current cursor position so we can restore it */
(void)lcd_read_busy_addr(priv, &addr);
- addr2rc(priv, addr, &row, &col);
- /* Just read the entire display into the given buffer, as much as possible */
+ /* Convert file position to row/col address and position DDADDR there */
- nIdx = 0;
- row = 0;
- col = 0;
+ lcd_fpos_to_curpos(priv, filep->f_pos, &row, &col, &onlf);
+ lcd_set_curpos(priv, row, col);
+
+ /* Read as much of the display as possible */
+ nIdx = 0;
while (nIdx < buflen && row < priv->cfg.rows)
{
+ /* Synthesize end-of-line LF and advance to start of next row */
+
+ if (onlf)
+ {
+ /* Synthesize LF for all but last row */
+
+ if ( row < priv->cfg.rows-1)
+ {
+ buffer[nIdx] = '\x0a';
+ onlf = false;
+ ++filep->f_pos;
+ ++nIdx;
+ }
+ ++row;
+ col = 0;
+ continue;
+ }
+
+ /* If we are at start of line we will need to update DDRAM address */
+
if (0 == col)
{
lcd_set_curpos(priv, row, 0);
@@ -1067,12 +1191,15 @@ static ssize_t pcf8574_lcd_read(FAR struct file *filep, FAR char *buffer,
buffer[nIdx] = lcd_getdata(priv);
+ ++filep->f_pos;
++nIdx;
++col;
+
+ /* If we are now at the end of a line, we setup for the synthetic LF */
+
if (priv->cfg.cols == col)
{
- ++row;
- col = 0;
+ onlf = true;
}
}
@@ -1226,10 +1353,62 @@ static ssize_t pcf8574_lcd_write(FAR struct file *filep,
}
}
+ /* Wherever we wound up, update our logical file pos to reflect it */
+
+ lcd_curpos_to_fpos(priv, row, col, &filep->f_pos);
+
sem_post(&priv->sem_excl);
return buflen;
}
+/****************************************************************************
+ * Name: pcf8574_lcd_seek
+ *
+ * Description:
+ * Seek the logical file pointer to the specified position. This is
+ * probably not very interesting except possibly for (SEEK_SET, 0) to
+ * rewind the pointer for a subsequent read().
+ * The file pointer is logical, and includes synthesized LF chars at the
+ * end of the display lines.
+ *
+ ****************************************************************************/
+
+static off_t pcf8574_lcd_seek(FAR struct file *filep, off_t offset, int whence)
+{
+ FAR struct inode *inode = filep->f_inode;
+ FAR struct pcf8574_lcd_dev_s *priv = (FAR struct pcf8574_lcd_dev_s *)inode->i_private;
+ int maxpos;
+
+ sem_wait(&priv->sem_excl);
+
+ maxpos = priv->cfg.rows * priv->cfg.cols + (priv->cfg.rows - 1);
+ switch (whence)
+ {
+ case SEEK_CUR:
+ filep->f_pos += offset;
+ if (filep->f_pos > maxpos)
+ filep->f_pos = maxpos;
+ break;
+
+ case SEEK_SET:
+ filep->f_pos = offset;
+ if (filep->f_pos > maxpos)
+ filep->f_pos = maxpos;
+ break;
+
+ case SEEK_END:
+ filep->f_pos = maxpos;
+ break;
+
+ default:
+ /* Return EINVAL if the whence argument is invalid */
+ filep->f_pos = -EINVAL;
+ }
+
+ sem_post(&priv->sem_excl);
+ return filep->f_pos;
+}
+
/****************************************************************************
* Name: pcf8574_lcd_ioctl
*
@@ -1349,6 +1528,32 @@ static int pcf8574lcd_poll(FAR struct file *filep, FAR struct pollfd *fds,
}
#endif
+/****************************************************************************
+ * Name: pcf8574_lcd_unlink
+ ****************************************************************************/
+
+#ifndef CONFIG_DISABLE_PSEUDOFS_OPERATIONS
+static int pcf8574_lcd_unlink(FAR struct inode *inode)
+{
+ FAR struct pcf8574_lcd_dev_s *priv = (FAR struct pcf8574_lcd_dev_s *)inode->i_private;
+ int ret = OK;
+
+ sem_wait(&priv->sem_excl);
+
+ priv->unlinked = true;
+
+ /* If there are no open references to the driver then tear it down now */
+ if (priv->refs == 0)
+ {
+ /* We have no real teardown at present */
+ ret = OK;
+ }
+
+ sem_post(&priv->sem_excl);
+ return ret;
+}
+#endif
+
/****************************************************************************
* Public Functions
****************************************************************************/
@@ -1395,6 +1600,8 @@ int pcf8574_lcd_backpack_register(FAR const char *devpath,
priv->i2c = i2c;
priv->cfg = *cfg;
priv->bl_bit = priv->cfg.bl_active_high ? 0 : (1 << priv->cfg.bl);
+ priv->refs = 0;
+ priv->unlinked = false;
sem_init(&priv->sem_excl, 0, 1);
/* Initialize */