sam4e8e: Move ADC code to new file afec.c

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

1 files changed, 218 insertions, 0 deletions

diff --git a/src/sam4e8e/afec.c b/src/sam4e8e/afec.c
new file mode 100644
index 00000000..f9a499bb
--- /dev/null
+++ b/src/sam4e8e/afec.c
@@ -0,0 +1,218 @@
+// SAM4e8e Analog Front-End Converter (AFEC) support
+//
+// Copyright (C) 2018  Florian Heilmann <Florian.Heilmann@gmx.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include "autoconf.h" // CONFIG_CLOCK_FREQ
+#include "command.h" // shutdown
+#include "gpio.h" // gpio_adc_setup
+#include "internal.h" // GPIO
+#include "sam4e.h" // AFEC0
+#include "sched.h" // sched_shutdown
+
+static const uint8_t afec0_pins[] = {
+    //remove first channel, since it offsets the channel number: GPIO('A', 8),
+    GPIO('A', 17), GPIO('A', 18), GPIO('A', 19),
+    GPIO('A', 20), GPIO('B', 0),  GPIO('B', 1), GPIO('C', 13),
+    GPIO('C', 15), GPIO('C', 12), GPIO('C', 29), GPIO('C', 30),
+    GPIO('C', 31), GPIO('C', 26), GPIO('C', 27), GPIO('C',0)
+};
+
+static const uint8_t afec1_pins[] = {
+    GPIO('B', 2), GPIO('B', 3), GPIO('A', 21), GPIO('A', 22),
+    GPIO('C', 1), GPIO('C', 2), GPIO('C', 3), GPIO('C', 4),
+    /* Artificially pad this array so we can safely iterate over it */
+    GPIO('B', 2), GPIO('B', 2), GPIO('B', 2), GPIO('B', 2),
+    GPIO('B', 2), GPIO('B', 2), GPIO('B', 2), GPIO('B', 2)
+};
+
+#define ADC_FREQ_MAX 6000000UL
+DECL_CONSTANT(ADC_MAX, 4095);
+
+static inline struct gpio_adc
+gpio_pin_to_afec(uint8_t pin)
+{
+    int chan;
+    Afec* afec_device;
+
+    for (chan=0; ; chan++) {
+        if (chan >= ARRAY_SIZE(afec0_pins))
+            shutdown("Not a valid ADC pin");
+        if (afec0_pins[chan] == pin) {
+            afec_device = AFEC0;
+            break;
+        }
+        if (afec1_pins[chan] == pin) {
+            afec_device = AFEC1;
+            break;
+        }
+    }
+    return (struct gpio_adc){.pin=pin, .chan=chan, .afec=afec_device};
+}
+
+static int
+init_afec(Afec* afec) {
+
+    // Enable PMC
+    if (afec == AFEC0)
+        PMC->PMC_PCER0 = 1 << ID_AFEC0;
+    else
+        PMC->PMC_PCER0 = 1 << ID_AFEC1;
+
+    // If busy, return busy
+    if ((afec->AFE_ISR & AFE_ISR_DRDY) == AFE_ISR_DRDY) {
+        return -1;
+    }
+
+    // Reset
+    afec->AFE_CR = AFE_CR_SWRST;
+
+    // Configure afec
+    afec->AFE_MR = AFE_MR_ANACH_ALLOWED | \
+                    AFE_MR_PRESCAL (SystemCoreClock / (2 * ADC_FREQ_MAX) -1) | \
+                    AFE_MR_SETTLING_AST3 | \
+                    AFE_MR_TRACKTIM(2) | \
+                    AFE_MR_TRANSFER(1) | \
+                    AFE_MR_STARTUP_SUT64;
+    afec->AFE_EMR = AFE_EMR_TAG | \
+                     AFE_EMR_RES_NO_AVERAGE | \
+                     AFE_EMR_STM;
+    afec->AFE_ACR = AFE_ACR_IBCTL(1);
+
+    // Disable interrupts
+    afec->AFE_IDR = 0xDF00803F;
+
+    // Disable SW triggering
+    uint32_t mr = afec->AFE_MR;
+
+    mr &= ~(AFE_MR_TRGSEL_Msk | AFE_MR_TRGEN | AFE_MR_FREERUN_ON);
+    mr |= AFE_MR_TRGEN_DIS;
+    afec->AFE_MR = mr;
+
+    return 0;
+}
+
+void
+gpio_afec_init(void) {
+
+    while(init_afec(AFEC0) != 0) {
+        (void)(AFEC0->AFE_LCDR & AFE_LCDR_LDATA_Msk);
+    }
+    while(init_afec(AFEC1) != 0) {
+        (void)(AFEC1->AFE_LCDR & AFE_LCDR_LDATA_Msk);
+    }
+
+}
+DECL_INIT(gpio_afec_init);
+
+struct gpio_adc
+gpio_adc_setup(uint8_t pin)
+{
+    struct gpio_adc adc_pin = gpio_pin_to_afec(pin);
+    Afec *afec = adc_pin.afec;
+
+    //config channel
+    uint32_t reg = afec->AFE_DIFFR;
+    reg &= ~(1u << adc_pin.chan);
+    afec->AFE_DIFFR = reg;
+    reg = afec->AFE_CGR;
+    reg &= ~(0x03u << (2 * adc_pin.chan));
+    reg |= 1 << (2 * adc_pin.chan);
+    afec->AFE_CGR = reg;
+
+    // Configure channel
+    // afec_ch_get_config_defaults(&ch_cfg);
+    // afec_ch_set_config(adc_pin.afec, adc_pin.chan, &ch_cfg);
+    // Remove default internal offset from channel
+    // See Atmel Appnote AT03078 Section 1.5
+    afec->AFE_CSELR = adc_pin.chan;
+    afec->AFE_COCR = (0x800 & AFE_COCR_AOFF_Msk);
+
+    // Enable and calibrate Channel
+    afec->AFE_CHER = 1 << adc_pin.chan;
+
+    reg = afec->AFE_CHSR;
+    afec->AFE_CDOR = reg;
+    afec->AFE_CR = AFE_CR_AUTOCAL;
+
+    return adc_pin;
+}
+
+enum { AFE_DUMMY=0xff };
+uint8_t active_channel_afec0 = AFE_DUMMY;
+uint8_t active_channel_afec1 = AFE_DUMMY;
+
+static inline uint8_t
+get_active_afec_channel(Afec* afec) {
+    if (afec == AFEC0) {
+        return active_channel_afec0;
+    }
+    return active_channel_afec1;
+}
+
+static inline void
+set_active_afec_channel(Afec* afec, uint8_t chan) {
+    if (afec == AFEC0) {
+        active_channel_afec0 = chan;
+    } else {
+        active_channel_afec1 = chan;
+    }
+}
+
+// Try to sample a value. Returns zero if sample ready, otherwise
+// returns the number of clock ticks the caller should wait before
+// retrying this function.
+uint32_t
+gpio_adc_sample(struct gpio_adc g)
+{
+    Afec* afec = g.afec;
+    if (get_active_afec_channel(afec) == g.chan) {
+        if ((afec->AFE_ISR & AFE_ISR_DRDY) && (afec->AFE_ISR & (1 << g.chan))) {
+            // Sample now ready
+            return 0;
+        } else {
+            // Busy
+            goto need_delay;
+        }
+    } else if (get_active_afec_channel(g.afec) != AFE_DUMMY) {
+        goto need_delay;
+    }
+
+    afec->AFE_CHDR = 0x803F; // Disable all channels
+    afec->AFE_CHER = 1 << g.chan;
+
+    set_active_afec_channel(afec, g.chan);
+
+    for (uint32_t chan = 0; chan < 16; ++chan)
+    {
+        if ((afec->AFE_ISR & (1 << chan)) != 0)
+        {
+            afec->AFE_CSELR = chan;
+            (void)(afec->AFE_CDR);
+        }
+    }
+    afec->AFE_CR = AFE_CR_START;
+
+need_delay:
+    return ADC_FREQ_MAX * 10000ULL / CONFIG_CLOCK_FREQ; // about 400 mcu clock cycles or 40 afec cycles
+}
+
+// Read a value; use only after gpio_adc_sample() returns zero
+uint16_t
+gpio_adc_read(struct gpio_adc g)
+{
+    Afec *afec = g.afec;
+    set_active_afec_channel(g.afec, AFE_DUMMY);
+    afec->AFE_CSELR = g.chan;
+    return afec->AFE_CDR;
+}
+
+// Cancel a sample that may have been started with gpio_adc_sample()
+void
+gpio_adc_cancel_sample(struct gpio_adc g)
+{
+    if (get_active_afec_channel(g.afec) == g.chan) {
+        set_active_afec_channel(g.afec, AFE_DUMMY);
+    }
+}