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
),