1// SPDX-License-Identifier: GPL-2.0+ 2/* 3 * (C) Copyright 2016 Stephen Warren <swarren@wwwdotorg.org> 4 * 5 * Derived from pl01x code: 6 * 7 * (C) Copyright 2000 8 * Rob Taylor, Flying Pig Systems. robt@flyingpig.com. 9 * 10 * (C) Copyright 2004 11 * ARM Ltd. 12 * Philippe Robin, <philippe.robin@arm.com> 13 */ 14 15/* Simple U-Boot driver for the BCM283x mini UART */ 16 17#include <common.h> 18#include <dm.h> 19#include <errno.h> 20#include <watchdog.h> 21#include <asm/gpio.h> 22#include <asm/io.h> 23#include <serial.h> 24#include <dm/platform_data/serial_bcm283x_mu.h> 25#include <dm/pinctrl.h> 26#include <linux/bitops.h> 27#include <linux/compiler.h> 28 29struct bcm283x_mu_regs { 30 u32 io; 31 u32 iir; 32 u32 ier; 33 u32 lcr; 34 u32 mcr; 35 u32 lsr; 36 u32 msr; 37 u32 scratch; 38 u32 cntl; 39 u32 stat; 40 u32 baud; 41}; 42 43#define BCM283X_MU_LCR_DATA_SIZE_8 3 44 45#define BCM283X_MU_LSR_TX_IDLE BIT(6) 46/* This actually means not full, but is named not empty in the docs */ 47#define BCM283X_MU_LSR_TX_EMPTY BIT(5) 48#define BCM283X_MU_LSR_RX_READY BIT(0) 49 50struct bcm283x_mu_priv { 51 struct bcm283x_mu_regs *regs; 52}; 53 54static int bcm283x_mu_serial_getc(struct udevice *dev); 55 56static int bcm283x_mu_serial_setbrg(struct udevice *dev, int baudrate) 57{ 58 struct bcm283x_mu_serial_plat *plat = dev_get_plat(dev); 59 struct bcm283x_mu_priv *priv = dev_get_priv(dev); 60 struct bcm283x_mu_regs *regs = priv->regs; 61 u32 divider; 62 63 if (plat->skip_init) 64 goto out; 65 66 divider = plat->clock / (baudrate * 8); 67 68 writel(BCM283X_MU_LCR_DATA_SIZE_8, ®s->lcr); 69 writel(divider - 1, ®s->baud); 70 71out: 72 /* Flush the RX queue - all data in there is bogus */ 73 while (bcm283x_mu_serial_getc(dev) != -EAGAIN) ; 74 75 return 0; 76} 77 78static int bcm283x_mu_serial_getc(struct udevice *dev) 79{ 80 struct bcm283x_mu_priv *priv = dev_get_priv(dev); 81 struct bcm283x_mu_regs *regs = priv->regs; 82 u32 data; 83 84 /* Wait until there is data in the FIFO */ 85 if (!(readl(®s->lsr) & BCM283X_MU_LSR_RX_READY)) 86 return -EAGAIN; 87 88 data = readl(®s->io); 89 90 return (int)data; 91} 92 93static int bcm283x_mu_serial_putc(struct udevice *dev, const char data) 94{ 95 struct bcm283x_mu_priv *priv = dev_get_priv(dev); 96 struct bcm283x_mu_regs *regs = priv->regs; 97 98 /* Wait until there is space in the FIFO */ 99 if (!(readl(®s->lsr) & BCM283X_MU_LSR_TX_EMPTY)) 100 return -EAGAIN; 101 102 /* Send the character */ 103 writel(data, ®s->io); 104 105 return 0; 106} 107 108static int bcm283x_mu_serial_pending(struct udevice *dev, bool input) 109{ 110 struct bcm283x_mu_priv *priv = dev_get_priv(dev); 111 struct bcm283x_mu_regs *regs = priv->regs; 112 unsigned int lsr; 113 114 lsr = readl(®s->lsr); 115 116 if (input) { 117 schedule(); 118 return (lsr & BCM283X_MU_LSR_RX_READY) ? 1 : 0; 119 } else { 120 return (lsr & BCM283X_MU_LSR_TX_IDLE) ? 0 : 1; 121 } 122} 123 124static const struct dm_serial_ops bcm283x_mu_serial_ops = { 125 .putc = bcm283x_mu_serial_putc, 126 .pending = bcm283x_mu_serial_pending, 127 .getc = bcm283x_mu_serial_getc, 128 .setbrg = bcm283x_mu_serial_setbrg, 129}; 130 131#if CONFIG_IS_ENABLED(OF_CONTROL) 132static const struct udevice_id bcm283x_mu_serial_id[] = { 133 {.compatible = "brcm,bcm2835-aux-uart"}, 134 {} 135}; 136 137/* 138 * Check if this serial device is muxed 139 * 140 * The serial device will only work properly if it has been muxed to the serial 141 * pins by firmware. Check whether that happened here. 142 * 143 * Return: true if serial device is muxed, false if not 144 */ 145static bool bcm283x_is_serial_muxed(void) 146{ 147 int serial_gpio = 15; 148 struct udevice *dev; 149 150 if (uclass_first_device_err(UCLASS_PINCTRL, &dev)) 151 return false; 152 153 if (pinctrl_get_gpio_mux(dev, 0, serial_gpio) != BCM2835_GPIO_ALT5) 154 return false; 155 156 return true; 157} 158 159static int bcm283x_mu_serial_probe(struct udevice *dev) 160{ 161 struct bcm283x_mu_serial_plat *plat = dev_get_plat(dev); 162 struct bcm283x_mu_priv *priv = dev_get_priv(dev); 163 fdt_addr_t addr; 164 165 /* Don't spawn the device if it's not muxed */ 166 if (!bcm283x_is_serial_muxed()) 167 return -ENODEV; 168 169 /* 170 * Read the ofdata here rather than in an of_to_plat() method 171 * since we need the soc simple-bus to be probed so that the 'ranges' 172 * property is used. 173 */ 174 addr = dev_read_addr(dev); 175 if (addr == FDT_ADDR_T_NONE) 176 return -EINVAL; 177 178 plat->base = addr; 179 plat->clock = dev_read_u32_default(dev, "clock", 1); 180 181 /* 182 * TODO: Reinitialization doesn't always work for now, just skip 183 * init always - we know we're already initialized 184 */ 185 plat->skip_init = true; 186 187 priv->regs = (struct bcm283x_mu_regs *)plat->base; 188 189 return 0; 190} 191#endif 192 193U_BOOT_DRIVER(serial_bcm283x_mu) = { 194 .name = "serial_bcm283x_mu", 195 .id = UCLASS_SERIAL, 196 .of_match = of_match_ptr(bcm283x_mu_serial_id), 197 .plat_auto = sizeof(struct bcm283x_mu_serial_plat), 198 .probe = bcm283x_mu_serial_probe, 199 .ops = &bcm283x_mu_serial_ops, 200#if !CONFIG_IS_ENABLED(OF_CONTROL) || IS_ENABLED(CONFIG_OF_BOARD) 201 .flags = DM_FLAG_PRE_RELOC, 202#endif 203 .priv_auto = sizeof(struct bcm283x_mu_priv), 204}; 205