2 * (C) Copyright 2016 Stephen Warren <swarren@wwwdotorg.org>
4 * Derived from pl01x code:
7 * Rob Taylor, Flying Pig Systems. robt@flyingpig.com.
11 * Philippe Robin, <philippe.robin@arm.com>
13 * SPDX-License-Identifier: GPL-2.0+
16 /* Simple U-Boot driver for the BCM283x mini UART */
25 #include <dm/platform_data/serial_bcm283x_mu.h>
26 #include <dm/pinctrl.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_setbrg(struct udevice *dev, int baudrate)
56 struct bcm283x_mu_serial_platdata *plat = dev_get_platdata(dev);
57 struct bcm283x_mu_priv *priv = dev_get_priv(dev);
58 struct bcm283x_mu_regs *regs = priv->regs;
64 divider = plat->clock / (baudrate * 8);
66 writel(BCM283X_MU_LCR_DATA_SIZE_8, ®s->lcr);
67 writel(divider - 1, ®s->baud);
72 static int bcm283x_mu_serial_probe(struct udevice *dev)
74 struct bcm283x_mu_serial_platdata *plat = dev_get_platdata(dev);
75 struct bcm283x_mu_priv *priv = dev_get_priv(dev);
77 priv->regs = (struct bcm283x_mu_regs *)plat->base;
82 static int bcm283x_mu_serial_getc(struct udevice *dev)
84 struct bcm283x_mu_priv *priv = dev_get_priv(dev);
85 struct bcm283x_mu_regs *regs = priv->regs;
88 /* Wait until there is data in the FIFO */
89 if (!(readl(®s->lsr) & BCM283X_MU_LSR_RX_READY))
92 data = readl(®s->io);
97 static int bcm283x_mu_serial_putc(struct udevice *dev, const char data)
99 struct bcm283x_mu_priv *priv = dev_get_priv(dev);
100 struct bcm283x_mu_regs *regs = priv->regs;
102 /* Wait until there is space in the FIFO */
103 if (!(readl(®s->lsr) & BCM283X_MU_LSR_TX_EMPTY))
106 /* Send the character */
107 writel(data, ®s->io);
112 static int bcm283x_mu_serial_pending(struct udevice *dev, bool input)
114 struct bcm283x_mu_priv *priv = dev_get_priv(dev);
115 struct bcm283x_mu_regs *regs = priv->regs;
118 lsr = readl(®s->lsr);
122 return (lsr & BCM283X_MU_LSR_RX_READY) ? 1 : 0;
124 return (lsr & BCM283X_MU_LSR_TX_IDLE) ? 0 : 1;
128 static const struct dm_serial_ops bcm283x_mu_serial_ops = {
129 .putc = bcm283x_mu_serial_putc,
130 .pending = bcm283x_mu_serial_pending,
131 .getc = bcm283x_mu_serial_getc,
132 .setbrg = bcm283x_mu_serial_setbrg,
135 #if CONFIG_IS_ENABLED(OF_CONTROL)
136 static const struct udevice_id bcm283x_mu_serial_id[] = {
137 {.compatible = "brcm,bcm2835-aux-uart"},
142 * Check if this serial device is muxed
144 * The serial device will only work properly if it has been muxed to the serial
145 * pins by firmware. Check whether that happened here.
147 * @return true if serial device is muxed, false if not
149 static bool bcm283x_is_serial_muxed(void)
151 int serial_gpio = 15;
154 if (uclass_first_device(UCLASS_PINCTRL, &dev) || !dev)
157 if (pinctrl_get_gpio_mux(dev, 0, serial_gpio) != BCM2835_GPIO_ALT5)
163 static int bcm283x_mu_serial_ofdata_to_platdata(struct udevice *dev)
165 struct bcm283x_mu_serial_platdata *plat = dev_get_platdata(dev);
168 /* Don't spawn the device if it's not muxed */
169 if (!bcm283x_is_serial_muxed())
172 addr = devfdt_get_addr(dev);
173 if (addr == FDT_ADDR_T_NONE)
177 plat->clock = dev_read_u32_default(dev, "clock", 1);
180 * TODO: Reinitialization doesn't always work for now, just skip
181 * init always - we know we're already initialized
183 plat->skip_init = true;
189 U_BOOT_DRIVER(serial_bcm283x_mu) = {
190 .name = "serial_bcm283x_mu",
192 .of_match = of_match_ptr(bcm283x_mu_serial_id),
193 .ofdata_to_platdata = of_match_ptr(bcm283x_mu_serial_ofdata_to_platdata),
194 .platdata_auto_alloc_size = sizeof(struct bcm283x_mu_serial_platdata),
195 .probe = bcm283x_mu_serial_probe,
196 .ops = &bcm283x_mu_serial_ops,
197 .flags = DM_FLAG_PRE_RELOC,
198 .priv_auto_alloc_size = sizeof(struct bcm283x_mu_priv),