--- /dev/null
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ */
+
+#include "ao.h"
+#include "ao_vga.h"
+
+/* VGA output from the SPI port
+ *
+ * Connections:
+ *
+ * STM VGA
+ * GND 4,6,7,8,9,10
+ * HSYNC PA5 13
+ * VSYNC PB5 14
+ * RGB PB4 1,2,3
+ *
+ * pixel clock PA8 -> PB3
+ * pixel enable PA1 -> PA15
+ */
+
+/* GRF formula for 640x480 yields a pixel clock very close to 24MHz. Pad by
+ * three scanlines to hit exactly that value
+ */
+
+#define HACTIVE (640)
+#define HSYNC_START (656)
+#define HSYNC_END (720)
+#define HTOTAL (800)
+
+#define VACTIVE 480
+#define VSYNC_START 481
+#define VSYNC_END 484
+#define VTOTAL 500
+
+/*
+ * The horizontal counter is set so that the end of hsync is reached
+ * at the maximum counter value. That means that the hblank interval
+ * is offset by HSYNC_END.
+ */
+
+#define HSYNC (HSYNC_END - HSYNC_START)
+#define HBLANK_END (HTOTAL - HSYNC_END)
+#define HBLANK_START (HBLANK_END + HACTIVE)
+
+/*
+ * The vertical counter is set so that the end of vsync is reached at
+ * the maximum counter value. That means that the vblank interval is
+ * offset by VSYNC_END. We send a blank line at the start of the
+ * frame, so each of these is off by one
+ */
+#define VSYNC (VSYNC_END - VSYNC_START)
+#define VBLANK_END (VTOTAL - VSYNC_END)
+#define VBLANK_START (VBLANK_END + VACTIVE)
+
+#define WIDTH_BYTES (AO_VGA_WIDTH >> 3)
+#define SCANOUT ((WIDTH_BYTES+2) >> 1)
+
+uint32_t ao_vga_fb[AO_VGA_STRIDE * AO_VGA_HEIGHT];
+
+const struct ao_bitmap ao_vga_bitmap = {
+ .base = ao_vga_fb,
+ .stride = AO_VGA_STRIDE,
+ .width = AO_VGA_WIDTH,
+ .height = AO_VGA_HEIGHT
+};
+
+static uint32_t *scanline;
+
+#define DMA_INDEX STM_DMA_INDEX(STM_DMA_CHANNEL_SPI1_TX)
+
+#define DMA_CCR(en) ((0 << STM_DMA_CCR_MEM2MEM) | \
+ (STM_DMA_CCR_PL_VERY_HIGH << STM_DMA_CCR_PL) | \
+ (STM_DMA_CCR_MSIZE_16 << STM_DMA_CCR_MSIZE) | \
+ (STM_DMA_CCR_PSIZE_16 << STM_DMA_CCR_PSIZE) | \
+ (1 << STM_DMA_CCR_MINC) | \
+ (0 << STM_DMA_CCR_PINC) | \
+ (0 << STM_DMA_CCR_CIRC) | \
+ (STM_DMA_CCR_DIR_MEM_TO_PER << STM_DMA_CCR_DIR) | \
+ (0 << STM_DMA_CCR_TCIE) | \
+ (en << STM_DMA_CCR_EN))
+
+
+void stm_tim2_isr(void)
+{
+ int16_t line = stm_tim3.cnt;
+
+ if (VBLANK_END <= line && line < VBLANK_START) {
+ /* Disable */
+ stm_dma.channel[DMA_INDEX].ccr = DMA_CCR(0);
+ /* Reset DMA engine for the next scanline */
+ stm_dma.channel[DMA_INDEX].cmar = scanline;
+ stm_dma.channel[DMA_INDEX].cndtr = SCANOUT;
+
+ /* reset SPI */
+ (void) stm_spi1.dr;
+ (void) stm_spi1.sr;
+
+ /* Enable */
+ stm_dma.channel[DMA_INDEX].ccr = DMA_CCR(1);
+ if (((line - VBLANK_END) & 1))
+ scanline += AO_VGA_STRIDE;
+ } else {
+ scanline = ao_vga_fb;
+ }
+ stm_tim2.sr = 0;
+}
+
+
+void
+ao_vga_init(void)
+{
+ uint32_t cfgr;
+
+ /* Initialize spi1 using MISO PB4 for output */
+ stm_rcc.ahbenr |= (1 << STM_RCC_AHBENR_GPIOBEN);
+ stm_rcc.ahbenr |= (1 << STM_RCC_AHBENR_GPIOAEN);
+
+ stm_ospeedr_set(&stm_gpiob, 4, STM_OSPEEDR_40MHz);
+ stm_afr_set(&stm_gpiob, 4, STM_AFR_AF5);
+ stm_afr_set(&stm_gpiob, 3, STM_AFR_AF5);
+ stm_afr_set(&stm_gpioa, 15, STM_AFR_AF5);
+
+ /* turn on SPI */
+ stm_rcc.apb2enr |= (1 << STM_RCC_APB2ENR_SPI1EN);
+
+ stm_spi1.cr1 = ((1 << STM_SPI_CR1_BIDIMODE) | /* Two wire mode */
+ (1 << STM_SPI_CR1_BIDIOE) |
+ (0 << STM_SPI_CR1_CRCEN) | /* CRC disabled */
+ (0 << STM_SPI_CR1_CRCNEXT) |
+ (1 << STM_SPI_CR1_DFF) |
+ (0 << STM_SPI_CR1_RXONLY) |
+ (0 << STM_SPI_CR1_SSM) | /* Software SS handling */
+ (1 << STM_SPI_CR1_SSI) | /* ... */
+ (1 << STM_SPI_CR1_LSBFIRST) | /* Little endian */
+ (1 << STM_SPI_CR1_SPE) | /* Enable SPI unit */
+ (0 << STM_SPI_CR1_BR) | /* baud rate to pclk/2 */
+ (0 << STM_SPI_CR1_MSTR) |
+ (0 << STM_SPI_CR1_CPOL) | /* Format 0 */
+ (0 << STM_SPI_CR1_CPHA));
+ stm_spi1.cr2 = ((0 << STM_SPI_CR2_TXEIE) |
+ (0 << STM_SPI_CR2_RXNEIE) |
+ (0 << STM_SPI_CR2_ERRIE) |
+ (0 << STM_SPI_CR2_SSOE) |
+ (1 << STM_SPI_CR2_TXDMAEN) |
+ (0 << STM_SPI_CR2_RXDMAEN));
+
+ (void) stm_spi1.dr;
+ (void) stm_spi1.sr;
+
+ /* Grab the DMA channel for SPI1 MOSI */
+ stm_dma.channel[DMA_INDEX].cpar = &stm_spi1.dr;
+ stm_dma.channel[DMA_INDEX].cmar = ao_vga_fb;
+
+ /*
+ * Hsync Configuration
+ */
+ /* Turn on timer 2 */
+ stm_rcc.apb1enr |= (1 << STM_RCC_APB1ENR_TIM2EN);
+
+ /* tim2 runs at full speed */
+ stm_tim2.psc = 0;
+
+ /* Disable channels while modifying */
+ stm_tim2.ccer = 0;
+
+ /* Channel 1 hsync PWM values */
+ stm_tim2.ccr1 = HSYNC;
+
+ /* Channel 2 trigger scanout */
+ /* wait for the time to start scanout */
+ stm_tim2.ccr2 = HBLANK_END;
+
+ stm_tim2.ccr3 = 32;
+
+ /* Configure channel 1 to output on the pin and
+ * channel 2 to to set the trigger for the vsync timer
+ */
+ stm_tim2.ccmr1 = ((0 << STM_TIM234_CCMR1_OC2CE) |
+ (STM_TIM234_CCMR1_OC2M_PWM_MODE_1 << STM_TIM234_CCMR1_OC2M) |
+ (1 << STM_TIM234_CCMR1_OC2PE) |
+ (0 << STM_TIM234_CCMR1_OC2FE) |
+ (STM_TIM234_CCMR1_CC2S_OUTPUT << STM_TIM234_CCMR1_CC2S) |
+
+ (0 << STM_TIM234_CCMR1_OC1CE) |
+ (STM_TIM234_CCMR1_OC1M_PWM_MODE_1 << STM_TIM234_CCMR1_OC1M) |
+ (1 << STM_TIM234_CCMR1_OC1PE) |
+ (0 << STM_TIM234_CCMR1_OC1FE) |
+ (STM_TIM234_CCMR1_CC1S_OUTPUT << STM_TIM234_CCMR1_CC1S));
+
+ stm_tim2.ccmr2 = ((0 << STM_TIM234_CCMR2_OC4CE) |
+ (0 << STM_TIM234_CCMR2_OC4M) |
+ (0 << STM_TIM234_CCMR2_OC4PE) |
+ (0 << STM_TIM234_CCMR2_OC4FE) |
+ (0 << STM_TIM234_CCMR2_CC4S) |
+
+ (0 << STM_TIM234_CCMR2_OC3CE) |
+ (STM_TIM234_CCMR2_OC3M_PWM_MODE_1 << STM_TIM234_CCMR2_OC3M) |
+ (1 << STM_TIM234_CCMR2_OC3PE) |
+ (0 << STM_TIM234_CCMR2_OC3FE) |
+ (0 << STM_TIM234_CCMR2_CC3S));
+
+ /* One scanline */
+ stm_tim2.arr = HTOTAL;
+
+ stm_tim2.cnt = 0;
+
+ /* Update the register contents */
+ stm_tim2.egr |= (1 << STM_TIM234_EGR_UG);
+
+ /* Enable the timer */
+
+ /* Enable the output */
+ stm_tim2.ccer = ((0 << STM_TIM234_CCER_CC2NP) |
+ (STM_TIM234_CCER_CC2P_ACTIVE_HIGH << STM_TIM234_CCER_CC2P) |
+ (1 << STM_TIM234_CCER_CC2E) |
+ (0 << STM_TIM234_CCER_CC1NP) |
+ (STM_TIM234_CCER_CC1P_ACTIVE_LOW << STM_TIM234_CCER_CC1P) |
+ (1 << STM_TIM234_CCER_CC1E));
+
+ stm_tim2.cr2 = ((0 << STM_TIM234_CR2_TI1S) |
+ (STM_TIM234_CR2_MMS_UPDATE << STM_TIM234_CR2_MMS) |
+ (0 << STM_TIM234_CR2_CCDS));
+
+ /* hsync is not a slave timer */
+ stm_tim2.smcr = 0;
+
+ /* Send an interrupt on channel 3 */
+ stm_tim2.dier = ((1 << STM_TIM234_DIER_CC3IE));
+
+ stm_tim2.cr1 = ((STM_TIM234_CR1_CKD_1 << STM_TIM234_CR1_CKD) |
+ (1 << STM_TIM234_CR1_ARPE) |
+ (STM_TIM234_CR1_CMS_EDGE << STM_TIM234_CR1_CMS) |
+ (STM_TIM234_CR1_DIR_UP << STM_TIM234_CR1_DIR) |
+ (0 << STM_TIM234_CR1_OPM) |
+ (1 << STM_TIM234_CR1_URS) |
+ (0 << STM_TIM234_CR1_UDIS) |
+ (0 << STM_TIM234_CR1_CEN));
+
+ /* Hsync is on PA5 which is Timer 2 CH1 output */
+ stm_rcc.ahbenr |= (1 << STM_RCC_AHBENR_GPIOAEN);
+ stm_ospeedr_set(&stm_gpioa, 5, STM_OSPEEDR_40MHz);
+ stm_afr_set(&stm_gpioa, 5, STM_AFR_AF1);
+
+ /* pixel transmit enable is on PA1 */
+ stm_rcc.ahbenr |= (1 << STM_RCC_AHBENR_GPIOAEN);
+ stm_ospeedr_set(&stm_gpioa, 1, STM_OSPEEDR_40MHz);
+ stm_afr_set(&stm_gpioa, 1, STM_AFR_AF1);
+
+ /*
+ * Vsync configuration
+ */
+
+ /* Turn on timer 3, slaved to timer 1 using ITR1 (table 61) */
+ stm_rcc.apb1enr |= (1 << STM_RCC_APB1ENR_TIM3EN);
+
+ /* No prescale */
+ stm_tim3.psc = 0;
+
+ /* Channel 1 or 2 vsync PWM values */
+ stm_tim3.ccr1 = VSYNC;
+ stm_tim3.ccr2 = VSYNC;
+
+ stm_tim3.ccmr1 = ((0 << STM_TIM234_CCMR1_OC2CE) |
+ (STM_TIM234_CCMR1_OC2M_PWM_MODE_1 << STM_TIM234_CCMR1_OC2M) |
+ (1 << STM_TIM234_CCMR1_OC2PE) |
+ (0 << STM_TIM234_CCMR1_OC2FE) |
+ (STM_TIM234_CCMR1_CC2S_OUTPUT << STM_TIM234_CCMR1_CC2S) |
+
+ (0 << STM_TIM234_CCMR1_OC1CE) |
+ (STM_TIM234_CCMR1_OC1M_PWM_MODE_1 << STM_TIM234_CCMR1_OC1M) |
+ (1 << STM_TIM234_CCMR1_OC1PE) |
+ (0 << STM_TIM234_CCMR1_OC1FE) |
+ (STM_TIM234_CCMR1_CC1S_OUTPUT << STM_TIM234_CCMR1_CC1S));
+
+ stm_tim3.arr = VTOTAL;
+ stm_tim3.cnt = 0;
+
+ /* Update the register contents */
+ stm_tim3.egr |= (1 << STM_TIM234_EGR_UG);
+
+ /* Enable the timer */
+
+ /* Enable the output */
+ stm_tim3.ccer = ((0 << STM_TIM234_CCER_CC1NP) |
+ (STM_TIM234_CCER_CC2P_ACTIVE_LOW << STM_TIM234_CCER_CC2P) |
+ (1 << STM_TIM234_CCER_CC2E) |
+ (STM_TIM234_CCER_CC1P_ACTIVE_LOW << STM_TIM234_CCER_CC1P) |
+ (1 << STM_TIM234_CCER_CC1E));
+
+ stm_tim3.cr2 = ((0 << STM_TIM234_CR2_TI1S) |
+ (STM_TIM234_CR2_MMS_UPDATE << STM_TIM234_CR2_MMS) |
+ (0 << STM_TIM234_CR2_CCDS));
+
+ stm_tim3.smcr = 0;
+ stm_tim3.smcr = ((0 << STM_TIM234_SMCR_ETP) |
+ (0 << STM_TIM234_SMCR_ECE) |
+ (STM_TIM234_SMCR_ETPS_OFF << STM_TIM234_SMCR_ETPS) |
+ (STM_TIM234_SMCR_ETF_NONE << STM_TIM234_SMCR_ETF) |
+ (0 << STM_TIM234_SMCR_MSM) |
+ (STM_TIM234_SMCR_TS_ITR1 << STM_TIM234_SMCR_TS) |
+ (0 << STM_TIM234_SMCR_OCCS) |
+ (STM_TIM234_SMCR_SMS_EXTERNAL_CLOCK << STM_TIM234_SMCR_SMS));
+
+ stm_tim3.dier = 0;
+
+ stm_tim3.cr1 = ((STM_TIM234_CR1_CKD_1 << STM_TIM234_CR1_CKD) |
+ (1 << STM_TIM234_CR1_ARPE) |
+ (STM_TIM234_CR1_CMS_EDGE << STM_TIM234_CR1_CMS) |
+ (STM_TIM234_CR1_DIR_UP << STM_TIM234_CR1_DIR) |
+ (0 << STM_TIM234_CR1_OPM) |
+ (1 << STM_TIM234_CR1_URS) |
+ (0 << STM_TIM234_CR1_UDIS) |
+ (1 << STM_TIM234_CR1_CEN));
+
+ /* Vsync is on PB5 which is is Timer 3 CH2 output */
+ stm_rcc.ahbenr |= (1 << STM_RCC_AHBENR_GPIOBEN);
+ stm_ospeedr_set(&stm_gpiob, 5, STM_OSPEEDR_40MHz);
+ stm_afr_set(&stm_gpiob, 5, STM_AFR_AF2);
+
+ /* Use MCO for the pixel clock, that appears on PA8 */
+ cfgr = stm_rcc.cfgr & ~((STM_RCC_CFGR_MCOPRE_MASK << STM_RCC_CFGR_MCOPRE) |
+ (STM_RCC_CFGR_MCOSEL_MASK << STM_RCC_CFGR_MCOSEL));
+
+ cfgr |= ((STM_RCC_CFGR_MCOPRE_DIV_2 << STM_RCC_CFGR_MCOPRE) |
+ (STM_RCC_CFGR_MCOSEL_SYSCLK << STM_RCC_CFGR_MCOSEL));
+
+ stm_rcc.cfgr = cfgr;
+
+ stm_ospeedr_set(&stm_gpioa, 8, STM_OSPEEDR_40MHz);
+ stm_afr_set(&stm_gpioa, 8, STM_AFR_AF0);
+
+ /* Enable the scanline interrupt */
+ stm_nvic_set_priority(STM_ISR_TIM2_POS, AO_STM_NVIC_NONMASK_PRIORITY);
+ stm_nvic_set_enable(STM_ISR_TIM2_POS);
+}
+
+uint8_t enabled;
+
+void
+ao_vga_enable(int enable)
+{
+ if (enable) {
+ if (!enabled) {
+ ++ao_task_minimize_latency;
+ enabled = 1;
+ }
+ stm_tim2.cr1 |= (1 << STM_TIM234_CR1_CEN);
+ } else {
+ if (enabled) {
+ --ao_task_minimize_latency;
+ enabled = 0;
+ }
+ stm_tim2.cr1 &= ~(1 << STM_TIM234_CR1_CEN);
+ }
+}
projects / fw / altos / commitdiff