Initial Release

spi/spi_flash/spi_flash.c

@@ -0,0 +1,154 @@
+/**
+ * Copyright (c) 2020 Raspberry Pi (Trading) Ltd.
+ *
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+// Example of reading/writing an external serial flash using the PL022 SPI interface
+
+#include <stdio.h>
+#include "pico/stdlib.h"
+#include "hardware/spi.h"
+
+#define FLASH_PAGE_SIZE        256
+#define FLASH_SECTOR_SIZE      4096
+
+#define FLASH_CMD_PAGE_PROGRAM 0x02
+#define FLASH_CMD_READ         0x03
+#define FLASH_CMD_STATUS       0x05
+#define FLASH_CMD_WRITE_EN     0x06
+#define FLASH_CMD_SECTOR_ERASE 0x20
+
+#define FLASH_STATUS_BUSY_MASK 0x01
+
+#define PIN_MISO 4
+#define PIN_CS   5
+#define PIN_SCK  6
+#define PIN_MOSI 7
+
+static inline void cs_select(uint cs_pin) {
+    asm volatile("nop \n nop \n nop"); // FIXME
+    gpio_put(cs_pin, 0);
+    asm volatile("nop \n nop \n nop"); // FIXME
+}
+
+static inline void cs_deselect(uint cs_pin) {
+    asm volatile("nop \n nop \n nop"); // FIXME
+    gpio_put(cs_pin, 1);
+    asm volatile("nop \n nop \n nop"); // FIXME
+}
+
+void __not_in_flash_func(flash_read)(spi_inst_t *spi, uint cs_pin, uint32_t addr, uint8_t *buf, size_t len) {
+    cs_select(cs_pin);
+    uint8_t cmdbuf[4] = {
+            FLASH_CMD_READ,
+            addr >> 16,
+            addr >> 8,
+            addr
+    };
+    spi_write_blocking(spi, cmdbuf, 4);
+    spi_read_blocking(spi, 0, buf, len);
+    cs_deselect(cs_pin);
+}
+
+void __not_in_flash_func(flash_write_enable)(spi_inst_t *spi, uint cs_pin) {
+    cs_select(cs_pin);
+    uint8_t cmd = FLASH_CMD_WRITE_EN;
+    spi_write_blocking(spi, &cmd, 1);
+    cs_deselect(cs_pin);
+}
+
+void __not_in_flash_func(flash_wait_done)(spi_inst_t *spi, uint cs_pin) {
+    uint8_t status;
+    do {
+        cs_select(cs_pin);
+        uint8_t buf[2] = {FLASH_CMD_STATUS, 0};
+        spi_write_read_blocking(spi, buf, buf, 2);
+        cs_deselect(cs_pin);
+        status = buf[1];
+    } while (status & FLASH_STATUS_BUSY_MASK);
+}
+
+void __not_in_flash_func(flash_sector_erase)(spi_inst_t *spi, uint cs_pin, uint32_t addr) {
+    uint8_t cmdbuf[4] = {
+            FLASH_CMD_SECTOR_ERASE,
+            addr >> 16,
+            addr >> 8,
+            addr
+    };
+    flash_write_enable(spi, cs_pin);
+    cs_select(cs_pin);
+    spi_write_blocking(spi, cmdbuf, 4);
+    cs_deselect(cs_pin);
+    flash_wait_done(spi, cs_pin);
+}
+
+void __not_in_flash_func(flash_page_program)(spi_inst_t *spi, uint cs_pin, uint32_t addr, uint8_t data[]) {
+    uint8_t cmdbuf[4] = {
+            FLASH_CMD_PAGE_PROGRAM,
+            addr >> 16,
+            addr >> 8,
+            addr
+    };
+    flash_write_enable(spi, cs_pin);
+    cs_select(cs_pin);
+    spi_write_blocking(spi, cmdbuf, 4);
+    spi_write_blocking(spi, data, FLASH_PAGE_SIZE);
+    cs_deselect(cs_pin);
+    flash_wait_done(spi, cs_pin);
+}
+
+void printbuf(uint8_t buf[FLASH_PAGE_SIZE]) {
+    for (int i = 0; i < FLASH_PAGE_SIZE; ++i) {
+        if (i % 16 == 15)
+            printf("%02x\n", buf[i]);
+        else
+            printf("%02x ", buf[i]);
+    }
+}
+
+int main() {
+    // Enable UART so we can print status output
+    stdio_init_all();
+
+    printf("SPI flash example\n");
+
+    // Enable SPI 0 at 1 MHz and connect to GPIOs
+    spi_init(spi0, 1000 * 1000);
+    gpio_set_function(PIN_MISO, GPIO_FUNC_SPI);
+    gpio_set_function(PIN_SCK, GPIO_FUNC_SPI);
+    gpio_set_function(PIN_MOSI, GPIO_FUNC_SPI);
+
+    // Chip select is active-low, so we'll initialise it to a driven-high state
+    gpio_init(PIN_CS);
+    gpio_put(PIN_CS, 1);
+    gpio_set_dir(PIN_CS, GPIO_OUT);
+
+    printf("SPI initialised, let's goooooo\n");
+
+    uint8_t page_buf[FLASH_PAGE_SIZE];
+
+    const uint32_t target_addr = 0;
+
+    flash_sector_erase(spi0, PIN_CS, target_addr);
+    flash_read(spi0, PIN_CS, target_addr, page_buf, FLASH_PAGE_SIZE);
+
+    printf("After erase:\n");
+    printbuf(page_buf);
+
+    for (int i = 0; i < FLASH_PAGE_SIZE; ++i)
+        page_buf[i] = i;
+    flash_page_program(spi0, PIN_CS, target_addr, page_buf);
+    flash_read(spi0, PIN_CS, target_addr, page_buf, FLASH_PAGE_SIZE);
+
+    printf("After program:\n");
+    printbuf(page_buf);
+
+    flash_sector_erase(spi0, PIN_CS, target_addr);
+    flash_read(spi0, PIN_CS, target_addr, page_buf, FLASH_PAGE_SIZE);
+
+    printf("Erase again:\n");
+    printbuf(page_buf);
+
+    return 0;
+}