1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * (c) 2015 Paul Thacker <paul.thacker (at) microchip.com> 4 * 5 */ 6 #include <common.h> 7 #include <clk.h> 8 #include <dm.h> 9 #include <serial.h> 10 #include <wait_bit.h> 11 #include <mach/pic32.h> 12 #include <dt-bindings/clock/microchip,clock.h> 13 14 DECLARE_GLOBAL_DATA_PTR; 15 16 /* UART Control Registers */ 17 #define U_MOD 0x00 18 #define U_MODCLR (U_MOD + _CLR_OFFSET) 19 #define U_MODSET (U_MOD + _SET_OFFSET) 20 #define U_STA 0x10 21 #define U_STACLR (U_STA + _CLR_OFFSET) 22 #define U_STASET (U_STA + _SET_OFFSET) 23 #define U_TXR 0x20 24 #define U_RXR 0x30 25 #define U_BRG 0x40 26 27 /* U_MOD bits */ 28 #define UART_ENABLE BIT(15) 29 30 /* U_STA bits */ 31 #define UART_RX_ENABLE BIT(12) 32 #define UART_TX_BRK BIT(11) 33 #define UART_TX_ENABLE BIT(10) 34 #define UART_TX_FULL BIT(9) 35 #define UART_TX_EMPTY BIT(8) 36 #define UART_RX_OVER BIT(1) 37 #define UART_RX_DATA_AVAIL BIT(0) 38 39 struct pic32_uart_priv { 40 void __iomem *base; 41 ulong uartclk; 42 }; 43 44 /* 45 * Initialize the serial port with the given baudrate. 46 * The settings are always 8 data bits, no parity, 1 stop bit, no start bits. 47 */ 48 static int pic32_serial_init(void __iomem *base, ulong clk, u32 baudrate) 49 { 50 u32 div = DIV_ROUND_CLOSEST(clk, baudrate * 16); 51 52 /* wait for TX FIFO to empty */ 53 wait_for_bit_le32(base + U_STA, UART_TX_EMPTY, 54 true, CONFIG_SYS_HZ, false); 55 56 /* send break */ 57 writel(UART_TX_BRK, base + U_STASET); 58 59 /* disable and clear mode */ 60 writel(0, base + U_MOD); 61 writel(0, base + U_STA); 62 63 /* set baud rate generator */ 64 writel(div - 1, base + U_BRG); 65 66 /* enable the UART for TX and RX */ 67 writel(UART_TX_ENABLE | UART_RX_ENABLE, base + U_STASET); 68 69 /* enable the UART */ 70 writel(UART_ENABLE, base + U_MODSET); 71 return 0; 72 } 73 74 /* Check whether any char pending in RX fifo */ 75 static int pic32_uart_pending_input(void __iomem *base) 76 { 77 /* check if rx buffer overrun error has occurred */ 78 if (readl(base + U_STA) & UART_RX_OVER) { 79 readl(base + U_RXR); 80 81 /* clear overrun error to keep receiving */ 82 writel(UART_RX_OVER, base + U_STACLR); 83 } 84 85 /* In PIC32 there is no way to know number of outstanding 86 * chars in rx-fifo. Only it can be known whether there is any. 87 */ 88 return readl(base + U_STA) & UART_RX_DATA_AVAIL; 89 } 90 91 static int pic32_uart_pending(struct udevice *dev, bool input) 92 { 93 struct pic32_uart_priv *priv = dev_get_priv(dev); 94 95 if (input) 96 return pic32_uart_pending_input(priv->base); 97 98 return !(readl(priv->base + U_STA) & UART_TX_EMPTY); 99 } 100 101 static int pic32_uart_setbrg(struct udevice *dev, int baudrate) 102 { 103 struct pic32_uart_priv *priv = dev_get_priv(dev); 104 105 return pic32_serial_init(priv->base, priv->uartclk, baudrate); 106 } 107 108 static int pic32_uart_putc(struct udevice *dev, const char ch) 109 { 110 struct pic32_uart_priv *priv = dev_get_priv(dev); 111 112 /* Check if Tx FIFO is full */ 113 if (readl(priv->base + U_STA) & UART_TX_FULL) 114 return -EAGAIN; 115 116 /* pump the char to tx buffer */ 117 writel(ch, priv->base + U_TXR); 118 119 return 0; 120 } 121 122 static int pic32_uart_getc(struct udevice *dev) 123 { 124 struct pic32_uart_priv *priv = dev_get_priv(dev); 125 126 /* return error if RX fifo is empty */ 127 if (!pic32_uart_pending_input(priv->base)) 128 return -EAGAIN; 129 130 /* read the character from rx buffer */ 131 return readl(priv->base + U_RXR) & 0xff; 132 } 133 134 static int pic32_uart_probe(struct udevice *dev) 135 { 136 struct pic32_uart_priv *priv = dev_get_priv(dev); 137 struct clk clk; 138 fdt_addr_t addr; 139 fdt_size_t size; 140 int ret; 141 142 /* get address */ 143 addr = fdtdec_get_addr_size(gd->fdt_blob, dev_of_offset(dev), "reg", 144 &size); 145 if (addr == FDT_ADDR_T_NONE) 146 return -EINVAL; 147 148 priv->base = ioremap(addr, size); 149 150 /* get clock rate */ 151 ret = clk_get_by_index(dev, 0, &clk); 152 if (ret < 0) 153 return ret; 154 priv->uartclk = clk_get_rate(&clk); 155 clk_free(&clk); 156 157 /* initialize serial */ 158 return pic32_serial_init(priv->base, priv->uartclk, CONFIG_BAUDRATE); 159 } 160 161 static const struct dm_serial_ops pic32_uart_ops = { 162 .putc = pic32_uart_putc, 163 .pending = pic32_uart_pending, 164 .getc = pic32_uart_getc, 165 .setbrg = pic32_uart_setbrg, 166 }; 167 168 static const struct udevice_id pic32_uart_ids[] = { 169 { .compatible = "microchip,pic32mzda-uart" }, 170 {} 171 }; 172 173 U_BOOT_DRIVER(pic32_serial) = { 174 .name = "pic32-uart", 175 .id = UCLASS_SERIAL, 176 .of_match = pic32_uart_ids, 177 .probe = pic32_uart_probe, 178 .ops = &pic32_uart_ops, 179 .flags = DM_FLAG_PRE_RELOC, 180 .priv_auto_alloc_size = sizeof(struct pic32_uart_priv), 181 }; 182 183 #ifdef CONFIG_DEBUG_UART_PIC32 184 #include <debug_uart.h> 185 186 static inline void _debug_uart_init(void) 187 { 188 void __iomem *base = (void __iomem *)CONFIG_DEBUG_UART_BASE; 189 190 pic32_serial_init(base, CONFIG_DEBUG_UART_CLOCK, CONFIG_BAUDRATE); 191 } 192 193 static inline void _debug_uart_putc(int ch) 194 { 195 writel(ch, CONFIG_DEBUG_UART_BASE + U_TXR); 196 } 197 198 DEBUG_UART_FUNCS 199 #endif 200
