Paul Thacker | 9e160ee | 2016-01-28 15:30:14 +0530 | [diff] [blame] | 1 | /* |
| 2 | * (c) 2015 Paul Thacker <paul.thacker@microchip.com> |
| 3 | * |
| 4 | * SPDX-License-Identifier: GPL-2.0+ |
| 5 | * |
| 6 | */ |
| 7 | #include <common.h> |
| 8 | #include <clk.h> |
| 9 | #include <dm.h> |
| 10 | #include <serial.h> |
| 11 | #include <wait_bit.h> |
| 12 | #include <mach/pic32.h> |
| 13 | #include <dt-bindings/clock/microchip,clock.h> |
| 14 | |
| 15 | DECLARE_GLOBAL_DATA_PTR; |
| 16 | |
| 17 | /* UART Control Registers */ |
| 18 | #define U_MOD 0x00 |
| 19 | #define U_MODCLR (U_MOD + _CLR_OFFSET) |
| 20 | #define U_MODSET (U_MOD + _SET_OFFSET) |
| 21 | #define U_STA 0x10 |
| 22 | #define U_STACLR (U_STA + _CLR_OFFSET) |
| 23 | #define U_STASET (U_STA + _SET_OFFSET) |
| 24 | #define U_TXR 0x20 |
| 25 | #define U_RXR 0x30 |
| 26 | #define U_BRG 0x40 |
| 27 | |
| 28 | /* U_MOD bits */ |
| 29 | #define UART_ENABLE BIT(15) |
| 30 | |
| 31 | /* U_STA bits */ |
| 32 | #define UART_RX_ENABLE BIT(12) |
| 33 | #define UART_TX_BRK BIT(11) |
| 34 | #define UART_TX_ENABLE BIT(10) |
| 35 | #define UART_TX_FULL BIT(9) |
| 36 | #define UART_TX_EMPTY BIT(8) |
| 37 | #define UART_RX_OVER BIT(1) |
| 38 | #define UART_RX_DATA_AVAIL BIT(0) |
| 39 | |
| 40 | struct pic32_uart_priv { |
| 41 | void __iomem *base; |
| 42 | ulong uartclk; |
| 43 | }; |
| 44 | |
| 45 | /* |
| 46 | * Initialize the serial port with the given baudrate. |
| 47 | * The settings are always 8 data bits, no parity, 1 stop bit, no start bits. |
| 48 | */ |
| 49 | static int pic32_serial_init(void __iomem *base, ulong clk, u32 baudrate) |
| 50 | { |
| 51 | u32 div = DIV_ROUND_CLOSEST(clk, baudrate * 16); |
| 52 | |
| 53 | /* wait for TX FIFO to empty */ |
| 54 | wait_for_bit(__func__, base + U_STA, UART_TX_EMPTY, |
| 55 | true, CONFIG_SYS_HZ, false); |
| 56 | |
| 57 | /* send break */ |
| 58 | writel(UART_TX_BRK, base + U_STASET); |
| 59 | |
| 60 | /* disable and clear mode */ |
| 61 | writel(0, base + U_MOD); |
| 62 | writel(0, base + U_STA); |
| 63 | |
| 64 | /* set baud rate generator */ |
| 65 | writel(div - 1, base + U_BRG); |
| 66 | |
| 67 | /* enable the UART for TX and RX */ |
| 68 | writel(UART_TX_ENABLE | UART_RX_ENABLE, base + U_STASET); |
| 69 | |
| 70 | /* enable the UART */ |
| 71 | writel(UART_ENABLE, base + U_MODSET); |
| 72 | return 0; |
| 73 | } |
| 74 | |
| 75 | /* Check whether any char pending in RX fifo */ |
| 76 | static int pic32_uart_pending_input(void __iomem *base) |
| 77 | { |
| 78 | /* check if rx buffer overrun error has occurred */ |
| 79 | if (readl(base + U_STA) & UART_RX_OVER) { |
| 80 | readl(base + U_RXR); |
| 81 | |
| 82 | /* clear overrun error to keep receiving */ |
| 83 | writel(UART_RX_OVER, base + U_STACLR); |
| 84 | } |
| 85 | |
| 86 | /* In PIC32 there is no way to know number of outstanding |
| 87 | * chars in rx-fifo. Only it can be known whether there is any. |
| 88 | */ |
| 89 | return readl(base + U_STA) & UART_RX_DATA_AVAIL; |
| 90 | } |
| 91 | |
| 92 | static int pic32_uart_pending(struct udevice *dev, bool input) |
| 93 | { |
| 94 | struct pic32_uart_priv *priv = dev_get_priv(dev); |
| 95 | |
| 96 | if (input) |
| 97 | return pic32_uart_pending_input(priv->base); |
| 98 | |
| 99 | return !(readl(priv->base + U_STA) & UART_TX_EMPTY); |
| 100 | } |
| 101 | |
| 102 | static int pic32_uart_setbrg(struct udevice *dev, int baudrate) |
| 103 | { |
| 104 | struct pic32_uart_priv *priv = dev_get_priv(dev); |
| 105 | |
| 106 | return pic32_serial_init(priv->base, priv->uartclk, baudrate); |
| 107 | } |
| 108 | |
| 109 | static int pic32_uart_putc(struct udevice *dev, const char ch) |
| 110 | { |
| 111 | struct pic32_uart_priv *priv = dev_get_priv(dev); |
| 112 | |
| 113 | /* Check if Tx FIFO is full */ |
| 114 | if (readl(priv->base + U_STA) & UART_TX_FULL) |
| 115 | return -EAGAIN; |
| 116 | |
| 117 | /* pump the char to tx buffer */ |
| 118 | writel(ch, priv->base + U_TXR); |
| 119 | |
| 120 | return 0; |
| 121 | } |
| 122 | |
| 123 | static int pic32_uart_getc(struct udevice *dev) |
| 124 | { |
| 125 | struct pic32_uart_priv *priv = dev_get_priv(dev); |
| 126 | |
| 127 | /* return error if RX fifo is empty */ |
| 128 | if (!pic32_uart_pending_input(priv->base)) |
| 129 | return -EAGAIN; |
| 130 | |
| 131 | /* read the character from rx buffer */ |
| 132 | return readl(priv->base + U_RXR) & 0xff; |
| 133 | } |
| 134 | |
| 135 | static int pic32_uart_probe(struct udevice *dev) |
| 136 | { |
| 137 | struct pic32_uart_priv *priv = dev_get_priv(dev); |
Stephen Warren | 135aa95 | 2016-06-17 09:44:00 -0600 | [diff] [blame] | 138 | struct clk clk; |
Paul Thacker | 9e160ee | 2016-01-28 15:30:14 +0530 | [diff] [blame] | 139 | fdt_addr_t addr; |
| 140 | fdt_size_t size; |
| 141 | int ret; |
| 142 | |
| 143 | /* get address */ |
Simon Glass | e160f7d | 2017-01-17 16:52:55 -0700 | [diff] [blame] | 144 | addr = fdtdec_get_addr_size(gd->fdt_blob, dev_of_offset(dev), "reg", |
| 145 | &size); |
Paul Thacker | 9e160ee | 2016-01-28 15:30:14 +0530 | [diff] [blame] | 146 | if (addr == FDT_ADDR_T_NONE) |
| 147 | return -EINVAL; |
| 148 | |
| 149 | priv->base = ioremap(addr, size); |
| 150 | |
| 151 | /* get clock rate */ |
Stephen Warren | 135aa95 | 2016-06-17 09:44:00 -0600 | [diff] [blame] | 152 | ret = clk_get_by_index(dev, 0, &clk); |
Paul Thacker | 9e160ee | 2016-01-28 15:30:14 +0530 | [diff] [blame] | 153 | if (ret < 0) |
| 154 | return ret; |
Stephen Warren | 135aa95 | 2016-06-17 09:44:00 -0600 | [diff] [blame] | 155 | priv->uartclk = clk_get_rate(&clk); |
| 156 | clk_free(&clk); |
Paul Thacker | 9e160ee | 2016-01-28 15:30:14 +0530 | [diff] [blame] | 157 | |
| 158 | /* initialize serial */ |
| 159 | return pic32_serial_init(priv->base, priv->uartclk, CONFIG_BAUDRATE); |
| 160 | } |
| 161 | |
| 162 | static const struct dm_serial_ops pic32_uart_ops = { |
| 163 | .putc = pic32_uart_putc, |
| 164 | .pending = pic32_uart_pending, |
| 165 | .getc = pic32_uart_getc, |
| 166 | .setbrg = pic32_uart_setbrg, |
| 167 | }; |
| 168 | |
| 169 | static const struct udevice_id pic32_uart_ids[] = { |
| 170 | { .compatible = "microchip,pic32mzda-uart" }, |
| 171 | {} |
| 172 | }; |
| 173 | |
| 174 | U_BOOT_DRIVER(pic32_serial) = { |
| 175 | .name = "pic32-uart", |
| 176 | .id = UCLASS_SERIAL, |
| 177 | .of_match = pic32_uart_ids, |
| 178 | .probe = pic32_uart_probe, |
| 179 | .ops = &pic32_uart_ops, |
| 180 | .flags = DM_FLAG_PRE_RELOC, |
| 181 | .priv_auto_alloc_size = sizeof(struct pic32_uart_priv), |
| 182 | }; |
| 183 | |
| 184 | #ifdef CONFIG_DEBUG_UART_PIC32 |
| 185 | #include <debug_uart.h> |
| 186 | |
| 187 | static inline void _debug_uart_init(void) |
| 188 | { |
| 189 | void __iomem *base = (void __iomem *)CONFIG_DEBUG_UART_BASE; |
| 190 | |
| 191 | pic32_serial_init(base, CONFIG_DEBUG_UART_CLOCK, CONFIG_BAUDRATE); |
| 192 | } |
| 193 | |
| 194 | static inline void _debug_uart_putc(int ch) |
| 195 | { |
| 196 | writel(ch, CONFIG_DEBUG_UART_BASE + U_TXR); |
| 197 | } |
| 198 | |
| 199 | DEBUG_UART_FUNCS |
| 200 | #endif |