root / hw / mcf_uart.c @ 20dcee94
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/*
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* ColdFire UART emulation.
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*
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* Copyright (c) 2007 CodeSourcery.
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*
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* This code is licenced under the GPL
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*/
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#include "vl.h" |
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typedef struct { |
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uint8_t mr[2];
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uint8_t sr; |
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uint8_t isr; |
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uint8_t imr; |
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uint8_t bg1; |
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uint8_t bg2; |
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uint8_t fifo[4];
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uint8_t tb; |
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int current_mr;
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int fifo_len;
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int tx_enabled;
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int rx_enabled;
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qemu_irq irq; |
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CharDriverState *chr; |
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} mcf_uart_state; |
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/* UART Status Register bits. */
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#define MCF_UART_RxRDY 0x01 |
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#define MCF_UART_FFULL 0x02 |
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#define MCF_UART_TxRDY 0x04 |
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#define MCF_UART_TxEMP 0x08 |
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#define MCF_UART_OE 0x10 |
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#define MCF_UART_PE 0x20 |
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#define MCF_UART_FE 0x40 |
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#define MCF_UART_RB 0x80 |
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/* Interrupt flags. */
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#define MCF_UART_TxINT 0x01 |
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#define MCF_UART_RxINT 0x02 |
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#define MCF_UART_DBINT 0x04 |
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#define MCF_UART_COSINT 0x80 |
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/* UMR1 flags. */
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#define MCF_UART_BC0 0x01 |
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#define MCF_UART_BC1 0x02 |
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#define MCF_UART_PT 0x04 |
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#define MCF_UART_PM0 0x08 |
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#define MCF_UART_PM1 0x10 |
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#define MCF_UART_ERR 0x20 |
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#define MCF_UART_RxIRQ 0x40 |
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#define MCF_UART_RxRTS 0x80 |
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static void mcf_uart_update(mcf_uart_state *s) |
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{ |
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s->isr &= ~(MCF_UART_TxINT | MCF_UART_RxINT); |
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if (s->sr & MCF_UART_TxRDY)
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s->isr |= MCF_UART_TxINT; |
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if ((s->sr & ((s->mr[0] & MCF_UART_RxIRQ) |
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? MCF_UART_FFULL : MCF_UART_RxRDY)) != 0)
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s->isr |= MCF_UART_RxINT; |
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qemu_set_irq(s->irq, (s->isr & s->imr) != 0);
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} |
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uint32_t mcf_uart_read(void *opaque, target_phys_addr_t addr)
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{ |
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mcf_uart_state *s = (mcf_uart_state *)opaque; |
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switch (addr & 0x3f) { |
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case 0x00: |
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return s->mr[s->current_mr];
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case 0x04: |
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return s->sr;
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case 0x0c: |
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{ |
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uint8_t val; |
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int i;
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if (s->fifo_len == 0) |
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return 0; |
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val = s->fifo[0];
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s->fifo_len--; |
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for (i = 0; i < s->fifo_len; i++) |
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s->fifo[i] = s->fifo[i + 1];
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s->sr &= ~MCF_UART_FFULL; |
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if (s->fifo_len == 0) |
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s->sr &= ~MCF_UART_RxRDY; |
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mcf_uart_update(s); |
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return val;
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} |
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case 0x10: |
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/* TODO: Implement IPCR. */
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return 0; |
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case 0x14: |
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return s->isr;
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case 0x18: |
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return s->bg1;
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case 0x1c: |
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return s->bg2;
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default:
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return 0; |
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} |
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} |
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/* Update TxRDY flag and set data if present and enabled. */
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static void mcf_uart_do_tx(mcf_uart_state *s) |
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{ |
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if (s->tx_enabled && (s->sr & MCF_UART_TxEMP) == 0) { |
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if (s->chr)
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qemu_chr_write(s->chr, (unsigned char *)&s->tb, 1); |
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s->sr |= MCF_UART_TxEMP; |
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} |
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if (s->tx_enabled) {
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s->sr |= MCF_UART_TxRDY; |
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} else {
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s->sr &= ~MCF_UART_TxRDY; |
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} |
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} |
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static void mcf_do_command(mcf_uart_state *s, uint8_t cmd) |
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{ |
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/* Misc command. */
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switch ((cmd >> 4) & 3) { |
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case 0: /* No-op. */ |
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break;
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case 1: /* Reset mode register pointer. */ |
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s->current_mr = 0;
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break;
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case 2: /* Reset receiver. */ |
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s->rx_enabled = 0;
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s->fifo_len = 0;
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s->sr &= ~(MCF_UART_RxRDY | MCF_UART_FFULL); |
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break;
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case 3: /* Reset transmitter. */ |
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s->tx_enabled = 0;
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s->sr |= MCF_UART_TxEMP; |
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s->sr &= ~MCF_UART_TxRDY; |
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break;
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case 4: /* Reset error status. */ |
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break;
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case 5: /* Reset break-change interrupt. */ |
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s->isr &= ~MCF_UART_DBINT; |
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break;
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case 6: /* Start break. */ |
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case 7: /* Stop break. */ |
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break;
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} |
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/* Transmitter command. */
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switch ((cmd >> 2) & 3) { |
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case 0: /* No-op. */ |
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break;
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case 1: /* Enable. */ |
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s->tx_enabled = 1;
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mcf_uart_do_tx(s); |
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break;
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case 2: /* Disable. */ |
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s->tx_enabled = 0;
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mcf_uart_do_tx(s); |
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break;
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case 3: /* Reserved. */ |
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fprintf(stderr, "mcf_uart: Bad TX command\n");
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break;
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} |
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/* Receiver command. */
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switch (cmd & 3) { |
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case 0: /* No-op. */ |
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break;
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case 1: /* Enable. */ |
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s->rx_enabled = 1;
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break;
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case 2: |
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s->rx_enabled = 0;
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break;
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case 3: /* Reserved. */ |
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fprintf(stderr, "mcf_uart: Bad RX command\n");
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break;
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} |
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} |
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void mcf_uart_write(void *opaque, target_phys_addr_t addr, uint32_t val) |
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{ |
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mcf_uart_state *s = (mcf_uart_state *)opaque; |
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switch (addr & 0x3f) { |
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case 0x00: |
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s->mr[s->current_mr] = val; |
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s->current_mr = 1;
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break;
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case 0x04: |
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/* CSR is ignored. */
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break;
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case 0x08: /* Command Register. */ |
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mcf_do_command(s, val); |
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break;
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case 0x0c: /* Transmit Buffer. */ |
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s->sr &= ~MCF_UART_TxEMP; |
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s->tb = val; |
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mcf_uart_do_tx(s); |
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break;
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case 0x10: |
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/* ACR is ignored. */
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break;
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case 0x14: |
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s->imr = val; |
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break;
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default:
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break;
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} |
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mcf_uart_update(s); |
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} |
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static void mcf_uart_reset(mcf_uart_state *s) |
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{ |
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s->fifo_len = 0;
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s->mr[0] = 0; |
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s->mr[1] = 0; |
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s->sr = MCF_UART_TxEMP; |
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s->tx_enabled = 0;
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s->rx_enabled = 0;
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s->isr = 0;
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s->imr = 0;
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} |
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static void mcf_uart_push_byte(mcf_uart_state *s, uint8_t data) |
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{ |
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/* Break events overwrite the last byte if the fifo is full. */
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if (s->fifo_len == 4) |
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s->fifo_len--; |
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s->fifo[s->fifo_len] = data; |
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s->fifo_len++; |
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s->sr |= MCF_UART_RxRDY; |
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if (s->fifo_len == 4) |
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s->sr |= MCF_UART_FFULL; |
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mcf_uart_update(s); |
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} |
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static void mcf_uart_event(void *opaque, int event) |
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{ |
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mcf_uart_state *s = (mcf_uart_state *)opaque; |
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switch (event) {
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case CHR_EVENT_BREAK:
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s->isr |= MCF_UART_DBINT; |
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mcf_uart_push_byte(s, 0);
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break;
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default:
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break;
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} |
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} |
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static int mcf_uart_can_receive(void *opaque) |
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{ |
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mcf_uart_state *s = (mcf_uart_state *)opaque; |
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return s->rx_enabled && (s->sr & MCF_UART_FFULL) == 0; |
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} |
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static void mcf_uart_receive(void *opaque, const uint8_t *buf, int size) |
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{ |
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mcf_uart_state *s = (mcf_uart_state *)opaque; |
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mcf_uart_push_byte(s, buf[0]);
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} |
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void *mcf_uart_init(qemu_irq irq, CharDriverState *chr)
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{ |
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mcf_uart_state *s; |
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s = qemu_mallocz(sizeof(mcf_uart_state));
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s->chr = chr; |
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s->irq = irq; |
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if (chr) {
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qemu_chr_add_handlers(chr, mcf_uart_can_receive, mcf_uart_receive, |
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mcf_uart_event, s); |
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} |
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mcf_uart_reset(s); |
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return s;
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} |
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static CPUReadMemoryFunc *mcf_uart_readfn[] = {
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mcf_uart_read, |
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mcf_uart_read, |
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mcf_uart_read |
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}; |
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static CPUWriteMemoryFunc *mcf_uart_writefn[] = {
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mcf_uart_write, |
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mcf_uart_write, |
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mcf_uart_write |
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}; |
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void mcf_uart_mm_init(target_phys_addr_t base, qemu_irq irq,
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CharDriverState *chr) |
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{ |
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mcf_uart_state *s; |
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int iomemtype;
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s = mcf_uart_init(irq, chr); |
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iomemtype = cpu_register_io_memory(0, mcf_uart_readfn,
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mcf_uart_writefn, s); |
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cpu_register_physical_memory(base, 0x40, iomemtype);
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} |