V4L/DVB (8625): saa7134: Add NEC prococol IR decoding capability

This patch adds the capability of decoding NEC protocol, received via GPIO18 line.
This GPIO port can trigger saa7134 IRQ.

A future improvement would be to make it a little more generic to work also
with GPIO16 line.

A pure IRQ code didn't work, since some delays were introduced on the tests we
did.

A possible approach would be to use polling at a rate of 2.5 ms or less. If a
new code were taken, a code similar to nec_task() could be used. However, this
would add an extra overhead to kernel, and will consume more power.

Due to that, we took an hybrid approach: an IRQ upper half to trigger when a
new key is received and a bottom half to convert pulse-distance into a keycode.

The bottom half is polling based, to improve performance. During the bottom
half proccess, GPIO18 IRQ line is disabled, preventing IRQ reentrancy and
improving performance a little bit.

Thanks to Sistema Fenix (http://www.sistemafenix.com.br/) for sponsoring this
development.

Signed-off-by: Gilberto <gilberto@sistemafenix.com.br>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

1 files changed, 134 insertions, 6 deletions

diff --git a/drivers/media/video/saa7134/saa7134-input.c b/drivers/media/video/saa7134/saa7134-input.c
index ad08d13dffdd..ac6beb2df83d 100644
--- a/drivers/media/video/saa7134/saa7134-input.c
+++ b/drivers/media/video/saa7134/saa7134-input.c
@@ -62,8 +62,11 @@ MODULE_PARM_DESC(disable_other_ir, "disable full codes of "
 #define i2cdprintk(fmt, arg...)    if (ir_debug) \
         printk(KERN_DEBUG "%s/ir: " fmt, ir->c.name , ## arg)
 
-/** rc5 functions */
+/* Helper functions for RC5 and NEC decoding at GPIO16 or GPIO18 */
 static int saa7134_rc5_irq(struct saa7134_dev *dev);
+static int saa7134_nec_irq(struct saa7134_dev *dev);
+static void nec_task(unsigned long data);
+static void saa7134_nec_timer(unsigned long data);
 
 /* -------------------- GPIO generic keycode builder -------------------- */
 
@@ -280,7 +283,9 @@ void saa7134_input_irq(struct saa7134_dev *dev)
 {
         struct card_ir *ir = dev->remote;
 
-        if (!ir->polling && !ir->rc5_gpio) {
+        if (ir->nec_gpio) {
+                saa7134_nec_irq(dev);
+        } else if (!ir->polling && !ir->rc5_gpio) {
                 build_key(dev);
         } else if (ir->rc5_gpio) {
                 saa7134_rc5_irq(dev);
@@ -316,6 +321,10 @@ void saa7134_ir_start(struct saa7134_dev *dev, struct card_ir *ir)
                 ir->addr = 0x17;
                 ir->rc5_key_timeout = ir_rc5_key_timeout;
                 ir->rc5_remote_gap = ir_rc5_remote_gap;
+        } else if (ir->nec_gpio) {
+                setup_timer(&ir->timer_keyup, saa7134_nec_timer,
+                            (unsigned long)dev);
+                tasklet_init(&ir->tlet, nec_task, (unsigned long)dev);
         }
 }
 
@@ -335,6 +344,7 @@ int saa7134_input_init1(struct saa7134_dev *dev)
         u32 mask_keyup   = 0;
         int polling      = 0;
         int rc5_gpio     = 0;
+        int nec_gpio     = 0;
         int ir_type      = IR_TYPE_OTHER;
         int err;
 
@@ -533,6 +543,7 @@ int saa7134_input_init1(struct saa7134_dev *dev)
         ir->mask_keyup   = mask_keyup;
         ir->polling      = polling;
         ir->rc5_gpio     = rc5_gpio;
+        ir->nec_gpio     = nec_gpio;
 
         /* init input device */
         snprintf(ir->name, sizeof(ir->name), "saa7134 IR (%s)",
@@ -675,8 +686,125 @@ static int saa7134_rc5_irq(struct saa7134_dev *dev)
         return 1;
 }
 
-/* ----------------------------------------------------------------------
- * Local variables:
- * c-basic-offset: 8
- * End:
+
+/* On NEC protocol, One has 2.25 ms, and zero has 1.125 ms
+   The first pulse (start) has 9 + 4.5 ms
  */
+
+static void saa7134_nec_timer(unsigned long data)
+{
+        struct saa7134_dev *dev = (struct saa7134_dev *) data;
+        struct card_ir *ir = dev->remote;
+
+        dprintk("Cancel key repeat\n");
+
+        ir_input_nokey(ir->dev, &ir->ir);
+}
+
+static void nec_task(unsigned long data)
+{
+        struct saa7134_dev *dev = (struct saa7134_dev *) data;
+        struct card_ir *ir;
+        struct timeval tv;
+        int count, pulse, oldpulse, gap;
+        u32 ircode = 0, not_code = 0;
+        int ngap = 0;
+
+        if (!data) {
+                printk(KERN_ERR "saa713x/ir: Can't recover dev struct\n");
+                /* GPIO will be kept disabled */
+                return;
+        }
+
+        ir = dev->remote;
+
+        /* rising SAA7134_GPIO_GPRESCAN reads the status */
+        saa_clearb(SAA7134_GPIO_GPMODE3, SAA7134_GPIO_GPRESCAN);
+        saa_setb(SAA7134_GPIO_GPMODE3, SAA7134_GPIO_GPRESCAN);
+
+        oldpulse = saa_readl(SAA7134_GPIO_GPSTATUS0 >> 2) & ir->mask_keydown;
+        pulse = oldpulse;
+
+        do_gettimeofday(&tv);
+        ir->base_time = tv;
+
+        /* Decode NEC pulsecode. This code can take up to 76.5 ms to run.
+           Unfortunately, using IRQ to decode pulse didn't work, since it uses
+           a pulse train of 38KHz. This means one pulse on each 52 us
+         */
+        do {
+                /* Wait until the end of pulse/space or 5 ms */
+                for (count = 0; count < 500; count++)  {
+                        udelay(10);
+                        /* rising SAA7134_GPIO_GPRESCAN reads the status */
+                        saa_clearb(SAA7134_GPIO_GPMODE3, SAA7134_GPIO_GPRESCAN);
+                        saa_setb(SAA7134_GPIO_GPMODE3, SAA7134_GPIO_GPRESCAN);
+                        pulse = saa_readl(SAA7134_GPIO_GPSTATUS0 >> 2)
+                                & ir->mask_keydown;
+                        if (pulse != oldpulse)
+                                break;
+                }
+
+                do_gettimeofday(&tv);
+                gap = 1000000 * (tv.tv_sec - ir->base_time.tv_sec) +
+                                tv.tv_usec - ir->base_time.tv_usec;
+
+                if (!pulse) {
+                        /* Bit 0 has 560 us, while bit 1 has 1120 us.
+                           Do something only if bit == 1
+                         */
+                        if (ngap && (gap > 560 + 280)) {
+                                unsigned int shift = ngap - 1;
+
+                                /* Address first, then command */
+                                if (shift < 8) {
+                                        shift += 8;
+                                        ircode |= 1 << shift;
+                                } else if (shift < 16) {
+                                        not_code |= 1 << shift;
+                                } else if (shift < 24) {
+                                        shift -= 16;
+                                        ircode |= 1 << shift;
+                                } else {
+                                        shift -= 24;
+                                        not_code |= 1 << shift;
+                                }
+                        }
+                        ngap++;
+                }
+
+
+                ir->base_time = tv;
+
+                /* TIMEOUT - Long pulse */
+                if (gap >= 5000)
+                        break;
+                oldpulse = pulse;
+        } while (ngap < 32);
+
+        if (ngap == 32) {
+                /* FIXME: should check if not_code == ~ircode */
+                ir->code = ir_extract_bits(ircode, ir->mask_keycode);
+
+                dprintk("scancode = 0x%02x (code = 0x%02x, notcode= 0x%02x)\n",
+                         ir->code, ircode, not_code);
+
+                ir_input_keydown(ir->dev, &ir->ir, ir->code, ir->code);
+        } else
+                dprintk("Repeat last key\n");
+
+        /* Keep repeating the last key */
+        mod_timer(&ir->timer_keyup, jiffies + msecs_to_jiffies(150));
+
+        saa_setl(SAA7134_IRQ2, SAA7134_IRQ2_INTE_GPIO18);
+}
+
+static int saa7134_nec_irq(struct saa7134_dev *dev)
+{
+        struct card_ir *ir = dev->remote;
+
+        saa_clearl(SAA7134_IRQ2, SAA7134_IRQ2_INTE_GPIO18);
+        tasklet_schedule(&ir->tlet);
+
+        return 1;
+}