[PATCH v2 2/3] soc: rockchip: add driver handling grf setup

[Heiko Stuebner]

The General Register Files are an area of registers containing a lot
of single-bit settings for numerous components as well full components
like usbphy control. Therefore all used components are accessed
via the syscon provided by the grf nodes or from the sub-devices
created through the simple-mfd created from the grf node.

Some settings are not used by anything but will need to be set up
according to expectations on the kernel side.

Best example is the force_jtag setting, which defaults to on and
results in the soc switching the pin-outputs between jtag and sdmmc
automatically depending on the card-detect status. This conflicts
heavily with how the dw_mmc driver expects to do its work and also
with the clock-controller, which has most likely deactivated the
jtag clock due to it being unused.

So far the handling of this setting was living in the mach-rockchip
code for the arm32-based rk3288 but that of course doesn't work
for arm64 socs and would also look ugly for further arm32 socs.

Also always disabling this setting is quite specific to linux and
its subsystems, other operating systems might prefer other settings,
so that the bootloader cannot really set a sane default for all.

So introduce a top-level driver for the grf that handles these
settings that need to be a certain way but nobody cares about.

Other needed settings might surface in the future and can then
be added here, but only as a last option. Ideally general GRF
settings should be handled in the driver needing them.

Signed-off-by: Heiko Stuebner <heiko at sntech.de>
---
 drivers/soc/rockchip/Kconfig  |  10 ++++
 drivers/soc/rockchip/Makefile |   1 +
 drivers/soc/rockchip/grf.c    | 134 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 145 insertions(+)
 create mode 100644 drivers/soc/rockchip/grf.c

diff --git a/drivers/soc/rockchip/Kconfig b/drivers/soc/rockchip/Kconfig
index 7140ff8..20da55d 100644
--- a/drivers/soc/rockchip/Kconfig
+++ b/drivers/soc/rockchip/Kconfig
@@ -3,6 +3,16 @@ if ARCH_ROCKCHIP || COMPILE_TEST
 #
 # Rockchip Soc drivers
 #
+
+config ROCKCHIP_GRF
+	bool
+	default y
+	help
+	  The General Register Files are a central component providing
+	  special additional settings registers for a lot of soc-components.
+	  In a lot of cases there also need to be default settings initialized
+	  to make some of them conform to expectations of the kernel.
+
 config ROCKCHIP_PM_DOMAINS
         bool "Rockchip generic power domain"
         depends on PM
diff --git a/drivers/soc/rockchip/Makefile b/drivers/soc/rockchip/Makefile
index 3d73d06..c851fa0 100644
--- a/drivers/soc/rockchip/Makefile
+++ b/drivers/soc/rockchip/Makefile
@@ -1,4 +1,5 @@
 #
 # Rockchip Soc drivers
 #
+obj-$(CONFIG_ROCKCHIP_GRF) += grf.o
 obj-$(CONFIG_ROCKCHIP_PM_DOMAINS) += pm_domains.o
diff --git a/drivers/soc/rockchip/grf.c b/drivers/soc/rockchip/grf.c
new file mode 100644
index 0000000..0c85476a
--- /dev/null
+++ b/drivers/soc/rockchip/grf.c
@@ -0,0 +1,134 @@
+/*
+ * Rockchip Generic Register Files setup
+ *
+ * Copyright (c) 2016 Heiko Stuebner <heiko at sntech.de>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/err.h>
+#include <linux/regmap.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/regmap.h>
+
+#define HIWORD_UPDATE(val, mask, shift) \
+		((val) << (shift) | (mask) << ((shift) + 16))
+
+struct rockchip_grf_value {
+	const char *desc;
+	u32 reg;
+	u32 val;
+};
+
+struct rockchip_grf_info {
+	const struct rockchip_grf_value *values;
+	int num_values;
+};
+
+#define RK3036_GRF_SOC_CON0		0x140
+
+static const struct rockchip_grf_value rk3036_defaults[] __initconst = {
+	/*
+	 * Disable auto jtag/sdmmc switching that causes issues with the
+	 * clock-framework and the mmc controllers making them unreliable.
+	 */
+	{ "jtag switching", RK3036_GRF_SOC_CON0, HIWORD_UPDATE(0, 1, 11) },
+};
+
+static const struct rockchip_grf_info rk3036_grf __initconst = {
+	.values = rk3036_defaults,
+	.num_values = ARRAY_SIZE(rk3036_defaults),
+};
+
+#define RK3288_GRF_SOC_CON0		0x244
+
+static const struct rockchip_grf_value rk3288_defaults[] __initconst = {
+	{ "jtag switching", RK3288_GRF_SOC_CON0, HIWORD_UPDATE(0, 1, 12) },
+};
+
+static const struct rockchip_grf_info rk3288_grf __initconst = {
+	.values = rk3288_defaults,
+	.num_values = ARRAY_SIZE(rk3288_defaults),
+};
+
+#define RK3368_GRF_SOC_CON15		0x43c
+
+static const struct rockchip_grf_value rk3368_defaults[] __initconst = {
+	{ "jtag switching", RK3368_GRF_SOC_CON15, HIWORD_UPDATE(0, 1, 13) },
+};
+
+static const struct rockchip_grf_info rk3368_grf __initconst = {
+	.values = rk3368_defaults,
+	.num_values = ARRAY_SIZE(rk3368_defaults),
+};
+
+#define RK3399_GRF_SOC_CON7		0xe21c
+
+static const struct rockchip_grf_value rk3399_defaults[] __initconst = {
+	{ "jtag switching", RK3399_GRF_SOC_CON7, HIWORD_UPDATE(0, 1, 12) },
+};
+
+static const struct rockchip_grf_info rk3399_grf __initconst = {
+	.values = rk3399_defaults,
+	.num_values = ARRAY_SIZE(rk3399_defaults),
+};
+
+static const struct of_device_id rockchip_grf_dt_match[] __initconst = {
+	{
+		.compatible = "rockchip,rk3036-grf",
+		.data = (void *)&rk3036_grf,
+	}, {
+		.compatible = "rockchip,rk3288-grf",
+		.data = (void *)&rk3288_grf,
+	}, {
+		.compatible = "rockchip,rk3368-grf",
+		.data = (void *)&rk3368_grf,
+	}, {
+		.compatible = "rockchip,rk3399-grf",
+		.data = (void *)&rk3399_grf,
+	},
+	{ /* sentinel */ },
+};
+
+static int __init rockchip_grf_init(void)
+{
+	const struct rockchip_grf_info *grf_info;
+	const struct of_device_id *match;
+	struct device_node *np;
+	struct regmap *grf;
+	int ret, i;
+
+	np = of_find_matching_node_and_match(NULL, rockchip_grf_dt_match, &match);
+	if (!np)
+		return -ENODEV;
+	if (!match || !match->data) {
+		pr_err("%s: missing grf data\n", __func__);
+		return -EINVAL;
+	}
+
+	grf_info = match->data;
+
+	grf = syscon_node_to_regmap(np);
+	if (IS_ERR(grf)) {
+		pr_err("%s: could not get grf syscon\n", __func__);
+		return PTR_ERR(grf);
+	}
+
+	for (i = 0; i < grf_info->num_values; i++) {
+		const struct rockchip_grf_value *val = &grf_info->values[i];
+
+		pr_debug("%s: adjusting %s in %#6x to %#10x\n", __func__,
+			val->desc, val->reg, val->val);
+		ret = regmap_write(grf, val->reg, val->val);
+		if (ret < 0)
+			pr_err("%s: write to %#6x failed with %d\n",
+			       __func__, val->reg, ret);
+	}
+
+	return 0;
+}
+postcore_initcall(rockchip_grf_init);
-- 
2.10.2