pressure.c: read_pressure()

Implement readout of the MS5534C pressure sensor.

gpio.h

@@ -96,6 +96,7 @@ static inline void init_gpio(void) {}
 #define SSP_SSEL_MASK1 0x03000000 // gpio1 pins to set high on deassert ssel
 #define SSP_SSEL_CONF0 0x00113f00 // ssel bits associated with gpio0 pins
 #define SSP_SSEL_CONF1 0x03ee0000 // ssel bits associated with gpio1 pins
+#define SSP_MISO (GPIO_FIO0PIN2 & 4)
 
 extern unsigned int gpio1_mask;
 void gpio_set(unsigned int pins);

pressure.c

@@ -47,3 +47,83 @@ int calib_pressure(int hashit)
 	pressure[idx] = ((8000+X)*10)>>5;
 	return idx;
 }
+
+static inline
+int pressure_wait_for_conversion(int timeout)
+{
+	while (SSP_MISO && timeout-->0);
+	return SSP_MISO;
+}
+
+int read_pressure(int from_phase, int to_phase, int value, struct ssp_config *sspc)
+{
+	static const unsigned short cmds[] = {
+		0b0000000010101010, //  0 reset part 1
+		0b1010101000000000, //  1 reset part 2
+		0b0001110101010000, //  2 word 1 cmd
+		0,                  //  3 word 1 value
+		0b0001110101100000, //  4 word 2 cmd
+		0,		    //  5 word 2 value
+		0b0001110110010000, //  6 word 3 cmd
+		0, 		    //  7 word 3 value
+		0b0001110110100000, //  8 word 4 cmd
+		0,		    //  9 word 5 value
+		0b0000111101000000, // 10 data 1 cmd
+		// wait
+		0,                  // 11 data 1,2 value
+		0b0000111100100000, // 12 data 2 cmd
+	};
+	int r = 0;
+	int timeout;
+	for (phase = from_phase; !r && phase <= to_phase; phase++)
+		switch (phase) {
+		case 0: if (!sspc)
+				sspc = spi_conf_bate;
+			ssp_init(sspc);
+			break;
+		case 1:
+			ssp_assert_ssel(ssp_ssel);
+			ssp_set_buffer(pressure_reading, 8);
+			ssp_set_match(0, 0, 3, 0, 8);
+			r = ssp_submit(cmds, 11, 0, 0);
+			break;
+		case 2:
+		case 6:
+		case 9: if (phase==to_phase)
+				timeout = value
+			else
+				timeout = 1000;
+			r = ssp_wait(timeout);
+			break;
+		case 3: pressure_reading[3] = pressure_reading[2];
+			pressure_reading[2] = pressure_reading[0];
+			pressure_reading[5] = pressure_reading[6];
+			break;
+		case 4:
+		case 7: if (phase==to_phase)
+				timeout = value;
+			else
+				timeout = 1000000;
+			r = pressure_wait_for_conversion(timeout);
+			break;
+		case 5: ssp_set_buffer(pressure_reading+6, 2);
+			ssp_set_match(0, 0, 0, 0, 0);
+			r = ssp_submit(cmds+11, 2, 0, 1);
+			break;
+		case 8: r = ssp_submit(cmds+11, 1, 0, 1);
+			break;
+		case 10:
+			ssp_deassert_ssel();
+			if (ssp_ssel & SSP_EXT)
+				pressure_reading[0] = 0xbafe;
+			else
+				pressure_reading[0] = 0xba7e;
+			break;
+		case 11:
+			calib_pressure(value);
+			break;
+		default:
+			r = -1;
+		}
+	return r;
+}

ssp.c

@@ -77,8 +77,8 @@ static void ssp_isr(void)
 		sr=SSPSR;
 		nread++;
 		ssp_lastword = ssp_lastword << ssp_bits | dr;
-		if (!rc
-		    && ssp_frame_count++ >= ssp_match_count
+		if (ssp_frame_count++ >= ssp_match_count
+		    && !rc
 		    && (dr & ssp_match_mask) == ssp_match_value) {
 			rc = ssp_read_size;
 			j->idle_count = 0;
@@ -173,7 +173,6 @@ void ssp_reset(void)
 	j->cmd_count = 0;
 	j->idle_count = 0;
 	j->read_count = 0;
-	ssp_set_buffer(0,0);
 	enable_irq(iflg);
 }
 
@@ -236,8 +235,9 @@ done:
 
 int ssp_wait(int timeout)
 {
-	while (ssp_busy() && timeout-->0);
-	return !timeout;
+	unsigned int c;
+	while ((c=ssp_busy()) && timeout-->0);
+	return c;
 }
 
 const struct ssp_config ssp_conf_adc =

ssp.h

@@ -3,7 +3,7 @@ void ssp_reset(void);
 
 void ssp_set_buffer(void *start, int size);
 void ssp_poll(void);
-int ssp_submit(unsigned short *cmd, int cmd_size, unsigned int idle, unsigned int compress);
+int ssp_submit(unsigned short *cmd, int cmd_size, unsigned int ic, unsigned int rc);
 int ssp_busy(void);
 int ssp_wait(int timeout);
 
@@ -47,3 +47,15 @@ extern const struct ssp_config ssp_conf_dac;
 extern const struct ssp_config ssp_conf_dac_daisy;
 extern const struct ssp_config ssp_conf_bate;
 extern const struct ssp_config ssp_conf_bate_ext;
+
+static inline
+void ssp_set_match(unsigned int mask, unsigned int value,
+		   unsigned int count, unsigned int idle,
+		   unsigned int size)
+{
+	ssp_idle = idle;
+	ssp_match_mask = mask;
+	ssp_match_value = value;
+	ssp_match_count = count;
+	ssp_read_size = size;
+}