1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Special driver to handle of-platdata
4 *
5 * Copyright 2019 Google LLC
6 *
7 * Some code from coreboot lpss.c
8 */
9
10#include <common.h>
11#include <dm.h>
12#include <dt-structs.h>
13#include <malloc.h>
14#include <ns16550.h>
15#include <spl.h>
16#include <asm/io.h>
17#include <asm/pci.h>
18#include <asm/lpss.h>
19#include <dm/device-internal.h>
20#include <asm/arch/uart.h>
21
22/* Low-power Subsystem (LPSS) clock register */
23enum {
24	LPSS_CLOCK_CTL_REG	= 0x200,
25	LPSS_CNT_CLOCK_EN	= 1,
26	LPSS_CNT_CLK_UPDATE	= 1U << 31,
27	LPSS_CLOCK_DIV_N_SHIFT	= 16,
28	LPSS_CLOCK_DIV_N_MASK	= 0x7fff << LPSS_CLOCK_DIV_N_SHIFT,
29	LPSS_CLOCK_DIV_M_SHIFT	= 1,
30	LPSS_CLOCK_DIV_M_MASK	= 0x7fff << LPSS_CLOCK_DIV_M_SHIFT,
31
32	/* These set the UART input clock speed */
33	LPSS_UART_CLK_M_VAL	= 0x25a,
34	LPSS_UART_CLK_N_VAL	= 0x7fff,
35};
36
37static void lpss_clk_update(void *regs, u32 clk_m_val, u32 clk_n_val)
38{
39	u32 clk_sel;
40
41	clk_sel = clk_n_val << LPSS_CLOCK_DIV_N_SHIFT |
42		 clk_m_val << LPSS_CLOCK_DIV_M_SHIFT;
43	clk_sel |= LPSS_CNT_CLK_UPDATE | LPSS_CNT_CLOCK_EN;
44
45	writel(clk_sel, regs + LPSS_CLOCK_CTL_REG);
46}
47
48static void uart_lpss_init(void *regs)
49{
50	/* Take UART out of reset */
51	lpss_reset_release(regs);
52
53	/* Set M and N divisor inputs and enable clock */
54	lpss_clk_update(regs, LPSS_UART_CLK_M_VAL, LPSS_UART_CLK_N_VAL);
55}
56
57void apl_uart_init(pci_dev_t bdf, ulong base)
58{
59	/* Set UART base address */
60	pci_x86_write_config(bdf, PCI_BASE_ADDRESS_0, base, PCI_SIZE_32);
61
62	/* Enable memory access and bus master */
63	pci_x86_write_config(bdf, PCI_COMMAND, PCI_COMMAND_MEMORY |
64			     PCI_COMMAND_MASTER, PCI_SIZE_32);
65
66	uart_lpss_init((void *)base);
67}
68
69/*
70 * This driver uses its own compatible string but almost everything else from
71 * the standard ns16550 driver. This allows us to provide an of-platdata
72 * implementation, since the platdata produced by of-platdata does not match
73 * struct apl_ns16550_plat.
74 *
75 * When running with of-platdata (generally TPL), the platdata is converted to
76 * something that ns16550 expects. When running withoutof-platdata (SPL, U-Boot
77 * proper), we use ns16550's of_to_plat routine.
78 */
79
80static int apl_ns16550_probe(struct udevice *dev)
81{
82	struct apl_ns16550_plat *plat = dev_get_plat(dev);
83
84	if (!CONFIG_IS_ENABLED(PCI))
85		apl_uart_init(plat->ns16550.bdf, plat->ns16550.base);
86
87	return ns16550_serial_probe(dev);
88}
89
90static int apl_ns16550_of_to_plat(struct udevice *dev)
91{
92#if CONFIG_IS_ENABLED(OF_PLATDATA)
93	struct dtd_intel_apl_ns16550 *dtplat;
94	struct apl_ns16550_plat *plat = dev_get_plat(dev);
95	struct ns16550_plat ns;
96
97	/*
98	 * The device's plat uses struct apl_ns16550_plat which starts with the
99	 * dtd struct, but the ns16550 driver expects it to be struct ns16550.
100	 * Set up what that driver expects. Note that this means that the values
101	 * cannot be read in this driver when using of-platdata.
102	 *
103	 * TODO(sjg@chromium.org): Consider having a separate plat pointer for
104	 * of-platdata so that it is not necessary to overwrite this.
105	 */
106	dtplat = &plat->dtplat;
107	ns.base = dtplat->early_regs[0];
108	ns.reg_width = 1;
109	ns.reg_shift = dtplat->reg_shift;
110	ns.reg_offset = 0;
111	ns.clock = dtplat->clock_frequency;
112	ns.fcr = UART_FCR_DEFVAL;
113	ns.bdf = pci_ofplat_get_devfn(dtplat->reg[0]);
114	memcpy(plat, &ns, sizeof(ns));
115#else
116	int ret;
117
118	ret = ns16550_serial_of_to_plat(dev);
119	if (ret)
120		return ret;
121#endif /* OF_PLATDATA */
122
123	return 0;
124}
125
126#if CONFIG_IS_ENABLED(OF_REAL)
127static const struct udevice_id apl_ns16550_serial_ids[] = {
128	{ .compatible = "intel,apl-ns16550" },
129	{ },
130};
131#endif
132
133U_BOOT_DRIVER(intel_apl_ns16550) = {
134	.name	= "intel_apl_ns16550",
135	.id	= UCLASS_SERIAL,
136	.of_match = of_match_ptr(apl_ns16550_serial_ids),
137	.plat_auto	= sizeof(struct apl_ns16550_plat),
138	.priv_auto	= sizeof(struct ns16550),
139	.ops	= &ns16550_serial_ops,
140	.of_to_plat = apl_ns16550_of_to_plat,
141	.probe = apl_ns16550_probe,
142};
143