1 // SPDX-License-Identifier: GPL-2.0+
3 * (C) Copyright 2016 Stephen Warren <swarren@wwwdotorg.org>
5 * Derived from pl01x code:
8 * Rob Taylor, Flying Pig Systems. robt@flyingpig.com.
12 * Philippe Robin, <philippe.robin@arm.com>
15 /* Simple U-Boot driver for the BCM283x mini UART */
24 #include <dm/platform_data/serial_bcm283x_mu.h>
25 #include <dm/pinctrl.h>
26 #include <linux/bitops.h>
27 #include <linux/compiler.h>
29 struct bcm283x_mu_regs {
43 #define BCM283X_MU_LCR_DATA_SIZE_8 3
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)
50 struct bcm283x_mu_priv {
51 struct bcm283x_mu_regs *regs;
54 static int bcm283x_mu_serial_getc(struct udevice *dev);
56 static int bcm283x_mu_serial_setbrg(struct udevice *dev, int baudrate)
58 struct bcm283x_mu_serial_platdata *plat = dev_get_platdata(dev);
59 struct bcm283x_mu_priv *priv = dev_get_priv(dev);
60 struct bcm283x_mu_regs *regs = priv->regs;
66 divider = plat->clock / (baudrate * 8);
68 writel(BCM283X_MU_LCR_DATA_SIZE_8, ®s->lcr);
69 writel(divider - 1, ®s->baud);
72 /* Flush the RX queue - all data in there is bogus */
73 while (bcm283x_mu_serial_getc(dev) != -EAGAIN) ;
78 static int bcm283x_mu_serial_getc(struct udevice *dev)
80 struct bcm283x_mu_priv *priv = dev_get_priv(dev);
81 struct bcm283x_mu_regs *regs = priv->regs;
84 /* Wait until there is data in the FIFO */
85 if (!(readl(®s->lsr) & BCM283X_MU_LSR_RX_READY))
88 data = readl(®s->io);
93 static int bcm283x_mu_serial_putc(struct udevice *dev, const char data)
95 struct bcm283x_mu_priv *priv = dev_get_priv(dev);
96 struct bcm283x_mu_regs *regs = priv->regs;
98 /* Wait until there is space in the FIFO */
99 if (!(readl(®s->lsr) & BCM283X_MU_LSR_TX_EMPTY))
102 /* Send the character */
103 writel(data, ®s->io);
108 static int bcm283x_mu_serial_pending(struct udevice *dev, bool input)
110 struct bcm283x_mu_priv *priv = dev_get_priv(dev);
111 struct bcm283x_mu_regs *regs = priv->regs;
114 lsr = readl(®s->lsr);
118 return (lsr & BCM283X_MU_LSR_RX_READY) ? 1 : 0;
120 return (lsr & BCM283X_MU_LSR_TX_IDLE) ? 0 : 1;
124 static 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,
131 #if CONFIG_IS_ENABLED(OF_CONTROL)
132 static const struct udevice_id bcm283x_mu_serial_id[] = {
133 {.compatible = "brcm,bcm2835-aux-uart"},
138 * Check if this serial device is muxed
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.
143 * @return true if serial device is muxed, false if not
145 static bool bcm283x_is_serial_muxed(void)
147 int serial_gpio = 15;
150 if (uclass_first_device(UCLASS_PINCTRL, &dev) || !dev)
153 if (pinctrl_get_gpio_mux(dev, 0, serial_gpio) != BCM2835_GPIO_ALT5)
159 static int bcm283x_mu_serial_probe(struct udevice *dev)
161 struct bcm283x_mu_serial_platdata *plat = dev_get_platdata(dev);
162 struct bcm283x_mu_priv *priv = dev_get_priv(dev);
165 /* Don't spawn the device if it's not muxed */
166 if (!bcm283x_is_serial_muxed())
170 * Read the ofdata here rather than in an ofdata_to_platdata() method
171 * since we need the soc simple-bus to be probed so that the 'ranges'
174 addr = devfdt_get_addr(dev);
175 if (addr == FDT_ADDR_T_NONE)
179 plat->clock = dev_read_u32_default(dev, "clock", 1);
182 * TODO: Reinitialization doesn't always work for now, just skip
183 * init always - we know we're already initialized
185 plat->skip_init = true;
187 priv->regs = (struct bcm283x_mu_regs *)plat->base;
193 U_BOOT_DRIVER(serial_bcm283x_mu) = {
194 .name = "serial_bcm283x_mu",
196 .of_match = of_match_ptr(bcm283x_mu_serial_id),
197 .platdata_auto_alloc_size = sizeof(struct bcm283x_mu_serial_platdata),
198 .probe = bcm283x_mu_serial_probe,
199 .ops = &bcm283x_mu_serial_ops,
200 #if !CONFIG_IS_ENABLED(OF_CONTROL) || CONFIG_IS_ENABLED(OF_BOARD)
201 .flags = DM_FLAG_PRE_RELOC,
203 .priv_auto_alloc_size = sizeof(struct bcm283x_mu_priv),