stm32: adc for new stm32f0 common code (#2120)

Derived from stm32/adc.c and stm32f0/adc.c with additional changes.

Tested on Monoprice Mini Delta (malyan) stm32f070xb board.

Signed-off-by: Chris Lombardi <clearchris@hotmail.com>

4 files changed, 144 insertions, 3 deletions

diff --git a/src/stm32/Kconfig b/src/stm32/Kconfig
index 378fb00b..af186416 100644
--- a/src/stm32/Kconfig
+++ b/src/stm32/Kconfig
@@ -6,7 +6,7 @@ config STM32_SELECT
     bool
     default y
     select HAVE_GPIO
-    select HAVE_GPIO_ADC if !MACH_STM32F0
+    select HAVE_GPIO_ADC
     select HAVE_GPIO_I2C if !MACH_STM32F0
     select HAVE_GPIO_SPI
     select HAVE_GPIO_BITBANGING
diff --git a/src/stm32/Makefile b/src/stm32/Makefile
index d05f6b24..79abc881 100644
--- a/src/stm32/Makefile
+++ b/src/stm32/Makefile
@@ -26,12 +26,13 @@ src-y += stm32/watchdog.c stm32/gpio.c generic/crc16_ccitt.c
 src-y += generic/armcm_boot.c generic/armcm_irq.c generic/armcm_reset.c
 src-$(CONFIG_MACH_STM32F0) += ../lib/stm32f0/system_stm32f0xx.c
 src-$(CONFIG_MACH_STM32F0) += generic/timer_irq.c stm32/stm32f0_timer.c
-src-$(CONFIG_MACH_STM32F0) += stm32/stm32f0.c
+src-$(CONFIG_MACH_STM32F0) += stm32/stm32f0.c stm32/stm32f0_adc.c
 src-$(CONFIG_MACH_STM32F1) += ../lib/stm32f1/system_stm32f1xx.c
 src-$(CONFIG_MACH_STM32F1) += stm32/stm32f1.c generic/armcm_timer.c
+src-$(CONFIG_MACH_STM32F1) += stm32/adc.c
 src-$(CONFIG_MACH_STM32F4) += ../lib/stm32f4/system_stm32f4xx.c
 src-$(CONFIG_MACH_STM32F4) += stm32/stm32f4.c generic/armcm_timer.c
-src-$(CONFIG_HAVE_GPIO_ADC) += stm32/adc.c
+src-$(CONFIG_MACH_STM32F4) += stm32/adc.c
 src-$(CONFIG_HAVE_GPIO_I2C) += stm32/i2c.c
 src-$(CONFIG_HAVE_GPIO_SPI) += stm32/spi.c
 usb-src-$(CONFIG_HAVE_STM32_USBFS) := stm32/usbfs.c
diff --git a/src/stm32/stm32f0.c b/src/stm32/stm32f0.c
index 26a3512c..f9eabeab 100644
--- a/src/stm32/stm32f0.c
+++ b/src/stm32/stm32f0.c
@@ -156,6 +156,16 @@ hsi48_setup(void)
 #endif
 }
 
+// Enable high speed internal 14Mhz clock for ADC
+static void
+hsi14_setup(void)
+{
+    // Enable HSI14 for ADC
+    RCC->CR2 = RCC_CR2_HSI14ON;
+    while (!(RCC->CR2 & RCC_CR2_HSI14RDY))
+        ;
+}
+
 // Main entry point - called from armcm_boot.c:ResetHandler()
 void
 armcm_main(void)
@@ -179,6 +189,9 @@ armcm_main(void)
     else
         pll_setup();
 
+    // Turn on hsi14 oscillator for ADC
+    hsi14_setup();
+
     // Support alternate USB pins on stm32f042
 #ifdef SYSCFG_CFGR1_PA11_PA12_RMP
     if (CONFIG_STM32F042_USB_PIN_SWAP) {
diff --git a/src/stm32/stm32f0_adc.c b/src/stm32/stm32f0_adc.c
new file mode 100644
index 00000000..21ef6a6a
--- /dev/null
+++ b/src/stm32/stm32f0_adc.c
@@ -0,0 +1,127 @@
+// ADC functions on STM32
+//
+// Copyright (C) 2019  Kevin O'Connor <kevin@koconnor.net>
+//
+// This file may be distributed under the terms of the GNU GPLv3 license.
+
+#include "board/irq.h" // irq_save
+#include "board/misc.h" // timer_from_us
+#include "command.h" // shutdown
+#include "compiler.h" // ARRAY_SIZE
+#include "generic/armcm_timer.h" // udelay
+#include "gpio.h" // gpio_adc_setup
+#include "internal.h" // GPIO
+#include "sched.h" // sched_shutdown
+
+DECL_CONSTANT("ADC_MAX", 4095);
+
+static const uint32_t adc_pins[][2] = {
+    {GPIO('A', 0), ADC_CHSELR_CHSEL0},
+    {GPIO('A', 1), ADC_CHSELR_CHSEL1},
+    {GPIO('A', 2), ADC_CHSELR_CHSEL2},
+    {GPIO('A', 3), ADC_CHSELR_CHSEL3},
+    {GPIO('A', 4), ADC_CHSELR_CHSEL4},
+    {GPIO('A', 5), ADC_CHSELR_CHSEL5},
+    {GPIO('A', 6), ADC_CHSELR_CHSEL6},
+    {GPIO('A', 7), ADC_CHSELR_CHSEL7},
+    {GPIO('B', 0), ADC_CHSELR_CHSEL8},
+    {GPIO('B', 1), ADC_CHSELR_CHSEL9},
+    {GPIO('C', 0), ADC_CHSELR_CHSEL10},
+    {GPIO('C', 1), ADC_CHSELR_CHSEL11},
+    {GPIO('C', 2), ADC_CHSELR_CHSEL12},
+    {GPIO('C', 3), ADC_CHSELR_CHSEL13},
+    {GPIO('C', 4), ADC_CHSELR_CHSEL14},
+    {GPIO('C', 5), ADC_CHSELR_CHSEL15}
+};
+
+struct gpio_adc
+gpio_adc_setup(uint32_t pin)
+{
+    // Find pin in adc_pins table
+    int chan;
+    for (chan=0; ; chan++) {
+        if (chan >= ARRAY_SIZE(adc_pins))
+            shutdown("Not a valid ADC pin");
+        if (adc_pins[chan][0] == pin)
+            break;
+    }
+
+    // Determine which ADC block to use
+    ADC_TypeDef *adc = ADC1;
+    uint32_t adc_base = ADC1_BASE;
+
+    // Enable the ADC
+    if (!is_enabled_pclock(adc_base)) {
+        enable_pclock(adc_base);
+
+        // 100: 41.5 ADC clock cycles
+        adc->SMPR |= (~ADC_SMPR_SMP_Msk | ADC_SMPR_SMP_2 );
+        adc->CFGR2 |= ADC_CFGR2_CKMODE;
+        adc->CFGR1 &= ~ADC_CFGR1_AUTOFF;
+        adc->CFGR1 |= ADC_CFGR1_EXTSEL;
+
+        // do not enable ADC before calibration
+        adc->CR &= ~ADC_CR_ADEN;
+        while (adc->CR & ADC_CR_ADEN)
+            ;
+        while (adc->CFGR1 & ADC_CFGR1_DMAEN)
+            ;
+        // start calibration and wait for completion
+        adc->CR |= ADC_CR_ADCAL;
+        while (adc->CR & ADC_CR_ADCAL)
+            ;
+
+        // if not enabled
+        if (!(adc->CR & ADC_CR_ADEN)){
+            adc->ISR |= ADC_ISR_ADRDY;
+            adc->CR |= ADC_CR_ADEN;
+            while (!(ADC1->ISR & ADC_ISR_ADRDY))
+                ;
+        }
+    }
+
+    gpio_peripheral(pin, GPIO_ANALOG, 0);
+
+    return (struct gpio_adc){ .adc = adc, .chan = adc_pins[chan][1] };
+}
+
+// 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)
+{
+    ADC_TypeDef *adc = g.adc;
+    if ((adc->ISR & ADC_ISR_EOC) && (adc->CHSELR == g.chan)){
+        return 0;
+    }
+    if (adc->CR & ADC_CR_ADSTART){
+       goto need_delay;
+    }
+    adc->CHSELR = g.chan;
+    adc->CR |= ADC_CR_ADSTART;
+
+need_delay:
+    return timer_from_us(10);
+}
+
+// Read a value; use only after gpio_adc_sample() returns zero
+uint16_t
+gpio_adc_read(struct gpio_adc g)
+{
+    ADC_TypeDef *adc = g.adc;
+    adc->ISR &= ~ADC_ISR_EOSEQ;
+    return adc->DR;
+}
+
+// Cancel a sample that may have been started with gpio_adc_sample()
+void
+gpio_adc_cancel_sample(struct gpio_adc g)
+{
+    ADC_TypeDef *adc = g.adc;
+    irqstatus_t flag = irq_save();
+    if (!(adc->ISR & ADC_ISR_EOC) && (adc->CHSELR == g.chan)){
+        adc->CR |= ADC_CR_ADSTP;
+    }
+    irq_restore(flag);
+}