clk: Add Baikal-T1 CCU Dividers driver

Nearly each Baikal-T1 IP-core is supposed to have a clock source
of particular frequency. But since there are greater than five
IP-blocks embedded into the SoC, the CCU PLLs can't fulfill all the
needs. Baikal-T1 CCU provides a set of fixed and configurable clock
dividers in order to generate a necessary signal for each chip
sub-block.

This driver creates the of-based hardware clocks for each divider
available in Baikal-T1 CCU. The same way as for PLLs we split the
functionality up into the clocks operations (gate, ungate, set rate,
etc) and hardware clocks declaration/registration procedures.

In accordance with the CCU documentation all its dividers are distributed
into two CCU sub-blocks: AXI-bus and system devices reference clocks.
The former sub-block is used to supply the clocks for AXI-bus interfaces
(AXI clock domains) and the later one provides the SoC IP-cores reference
clocks. Each sub-block is represented by a dedicated DT node, so they
have different compatible strings to distinguish one from another.

For some reason CCU provides the dividers of different types. Some
dividers can be gateable some can't, some are fixed while the others
are variable, some have special divider' limitations, some've got a
non-standard register layout and so on. In order to cover all of these
cases the hardware clocks driver is designed with an info-descriptor
pattern. So there are special static descriptors declared for the
dividers of each type with additional flags describing the block
peculiarity. These descriptors are then used to create hardware clocks
with proper operations.

Some CCU dividers provide a way to reset a domain they generate
a clock for. So the CCU AXI-bus and CCU system devices clock
drivers also perform the reset controller registration.

Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru>
Cc: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Rob Herring <robh+dt@kernel.org>
Cc: linux-mips@vger.kernel.org
Cc: devicetree@vger.kernel.org
Link: https://lore.kernel.org/r/20200526222056.18072-5-Sergey.Semin@baikalelectronics.ru
[sboyd@kernel.org: Drop return from void function, silence sparse
warnings about initializing structs with NULL vs. integer]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

1 files changed, 485 insertions, 0 deletions

diff --git a/drivers/clk/baikal-t1/clk-ccu-div.c b/drivers/clk/baikal-t1/clk-ccu-div.c
new file mode 100644
index 000000000000..b479156e5e9b
--- /dev/null
+++ b/drivers/clk/baikal-t1/clk-ccu-div.c
@@ -0,0 +1,485 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2020 BAIKAL ELECTRONICS, JSC
+ *
+ * Authors:
+ *   Serge Semin <Sergey.Semin@baikalelectronics.ru>
+ *   Dmitry Dunaev <dmitry.dunaev@baikalelectronics.ru>
+ *
+ * Baikal-T1 CCU Dividers clock driver
+ */
+
+#define pr_fmt(fmt) "bt1-ccu-div: " fmt
+
+#include <linux/kernel.h>
+#include <linux/printk.h>
+#include <linux/slab.h>
+#include <linux/clk-provider.h>
+#include <linux/reset-controller.h>
+#include <linux/mfd/syscon.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/ioport.h>
+#include <linux/regmap.h>
+
+#include <dt-bindings/clock/bt1-ccu.h>
+#include <dt-bindings/reset/bt1-ccu.h>
+
+#include "ccu-div.h"
+
+#define CCU_AXI_MAIN_BASE		0x030
+#define CCU_AXI_DDR_BASE		0x034
+#define CCU_AXI_SATA_BASE		0x038
+#define CCU_AXI_GMAC0_BASE		0x03C
+#define CCU_AXI_GMAC1_BASE		0x040
+#define CCU_AXI_XGMAC_BASE		0x044
+#define CCU_AXI_PCIE_M_BASE		0x048
+#define CCU_AXI_PCIE_S_BASE		0x04C
+#define CCU_AXI_USB_BASE		0x050
+#define CCU_AXI_HWA_BASE		0x054
+#define CCU_AXI_SRAM_BASE		0x058
+
+#define CCU_SYS_SATA_REF_BASE		0x060
+#define CCU_SYS_APB_BASE		0x064
+#define CCU_SYS_GMAC0_BASE		0x068
+#define CCU_SYS_GMAC1_BASE		0x06C
+#define CCU_SYS_XGMAC_BASE		0x070
+#define CCU_SYS_USB_BASE		0x074
+#define CCU_SYS_PVT_BASE		0x078
+#define CCU_SYS_HWA_BASE		0x07C
+#define CCU_SYS_UART_BASE		0x084
+#define CCU_SYS_TIMER0_BASE		0x088
+#define CCU_SYS_TIMER1_BASE		0x08C
+#define CCU_SYS_TIMER2_BASE		0x090
+#define CCU_SYS_WDT_BASE		0x150
+
+#define CCU_DIV_VAR_INFO(_id, _name, _pname, _base, _width, _flags, _features) \
+	{								\
+		.id = _id,						\
+		.name = _name,						\
+		.parent_name = _pname,					\
+		.base = _base,						\
+		.type = CCU_DIV_VAR,					\
+		.width = _width,					\
+		.flags = _flags,					\
+		.features = _features					\
+	}
+
+#define CCU_DIV_GATE_INFO(_id, _name, _pname, _base, _divider)	\
+	{							\
+		.id = _id,					\
+		.name = _name,					\
+		.parent_name = _pname,				\
+		.base = _base,					\
+		.type = CCU_DIV_GATE,				\
+		.divider = _divider				\
+	}
+
+#define CCU_DIV_FIXED_INFO(_id, _name, _pname, _divider)	\
+	{							\
+		.id = _id,					\
+		.name = _name,					\
+		.parent_name = _pname,				\
+		.type = CCU_DIV_FIXED,				\
+		.divider = _divider				\
+	}
+
+#define CCU_DIV_RST_MAP(_rst_id, _clk_id)	\
+	{					\
+		.rst_id = _rst_id,		\
+		.clk_id = _clk_id		\
+	}
+
+struct ccu_div_info {
+	unsigned int id;
+	const char *name;
+	const char *parent_name;
+	unsigned int base;
+	enum ccu_div_type type;
+	union {
+		unsigned int width;
+		unsigned int divider;
+	};
+	unsigned long flags;
+	unsigned long features;
+};
+
+struct ccu_div_rst_map {
+	unsigned int rst_id;
+	unsigned int clk_id;
+};
+
+struct ccu_div_data {
+	struct device_node *np;
+	struct regmap *sys_regs;
+
+	unsigned int divs_num;
+	const struct ccu_div_info *divs_info;
+	struct ccu_div **divs;
+
+	unsigned int rst_num;
+	const struct ccu_div_rst_map *rst_map;
+	struct reset_controller_dev rcdev;
+};
+#define to_ccu_div_data(_rcdev) container_of(_rcdev, struct ccu_div_data, rcdev)
+
+/*
+ * AXI Main Interconnect (axi_main_clk) and DDR AXI-bus (axi_ddr_clk) clocks
+ * must be left enabled in any case, since former one is responsible for
+ * clocking a bus between CPU cores and the rest of the SoC components, while
+ * the later is clocking the AXI-bus between DDR controller and the Main
+ * Interconnect. So should any of these clocks get to be disabled, the system
+ * will literally stop working. That's why we marked them as critical.
+ */
+static const struct ccu_div_info axi_info[] = {
+	CCU_DIV_VAR_INFO(CCU_AXI_MAIN_CLK, "axi_main_clk", "pcie_clk",
+			 CCU_AXI_MAIN_BASE, 4,
+			 CLK_IS_CRITICAL, CCU_DIV_RESET_DOMAIN),
+	CCU_DIV_VAR_INFO(CCU_AXI_DDR_CLK, "axi_ddr_clk", "sata_clk",
+			 CCU_AXI_DDR_BASE, 4,
+			 CLK_IS_CRITICAL | CLK_SET_RATE_GATE,
+			 CCU_DIV_RESET_DOMAIN),
+	CCU_DIV_VAR_INFO(CCU_AXI_SATA_CLK, "axi_sata_clk", "sata_clk",
+			 CCU_AXI_SATA_BASE, 4,
+			 CLK_SET_RATE_GATE, CCU_DIV_RESET_DOMAIN),
+	CCU_DIV_VAR_INFO(CCU_AXI_GMAC0_CLK, "axi_gmac0_clk", "eth_clk",
+			 CCU_AXI_GMAC0_BASE, 4,
+			 CLK_SET_RATE_GATE, CCU_DIV_RESET_DOMAIN),
+	CCU_DIV_VAR_INFO(CCU_AXI_GMAC1_CLK, "axi_gmac1_clk", "eth_clk",
+			 CCU_AXI_GMAC1_BASE, 4,
+			 CLK_SET_RATE_GATE, CCU_DIV_RESET_DOMAIN),
+	CCU_DIV_VAR_INFO(CCU_AXI_XGMAC_CLK, "axi_xgmac_clk", "eth_clk",
+			 CCU_AXI_XGMAC_BASE, 4,
+			 CLK_SET_RATE_GATE, CCU_DIV_RESET_DOMAIN),
+	CCU_DIV_VAR_INFO(CCU_AXI_PCIE_M_CLK, "axi_pcie_m_clk", "pcie_clk",
+			 CCU_AXI_PCIE_M_BASE, 4,
+			 CLK_SET_RATE_GATE, CCU_DIV_RESET_DOMAIN),
+	CCU_DIV_VAR_INFO(CCU_AXI_PCIE_S_CLK, "axi_pcie_s_clk", "pcie_clk",
+			 CCU_AXI_PCIE_S_BASE, 4,
+			 CLK_SET_RATE_GATE, CCU_DIV_RESET_DOMAIN),
+	CCU_DIV_VAR_INFO(CCU_AXI_USB_CLK, "axi_usb_clk", "sata_clk",
+			 CCU_AXI_USB_BASE, 4,
+			 CLK_SET_RATE_GATE, CCU_DIV_RESET_DOMAIN),
+	CCU_DIV_VAR_INFO(CCU_AXI_HWA_CLK, "axi_hwa_clk", "sata_clk",
+			 CCU_AXI_HWA_BASE, 4,
+			 CLK_SET_RATE_GATE, CCU_DIV_RESET_DOMAIN),
+	CCU_DIV_VAR_INFO(CCU_AXI_SRAM_CLK, "axi_sram_clk", "eth_clk",
+			 CCU_AXI_SRAM_BASE, 4,
+			 CLK_SET_RATE_GATE, CCU_DIV_RESET_DOMAIN)
+};
+
+static const struct ccu_div_rst_map axi_rst_map[] = {
+	CCU_DIV_RST_MAP(CCU_AXI_MAIN_RST, CCU_AXI_MAIN_CLK),
+	CCU_DIV_RST_MAP(CCU_AXI_DDR_RST, CCU_AXI_DDR_CLK),
+	CCU_DIV_RST_MAP(CCU_AXI_SATA_RST, CCU_AXI_SATA_CLK),
+	CCU_DIV_RST_MAP(CCU_AXI_GMAC0_RST, CCU_AXI_GMAC0_CLK),
+	CCU_DIV_RST_MAP(CCU_AXI_GMAC1_RST, CCU_AXI_GMAC1_CLK),
+	CCU_DIV_RST_MAP(CCU_AXI_XGMAC_RST, CCU_AXI_XGMAC_CLK),
+	CCU_DIV_RST_MAP(CCU_AXI_PCIE_M_RST, CCU_AXI_PCIE_M_CLK),
+	CCU_DIV_RST_MAP(CCU_AXI_PCIE_S_RST, CCU_AXI_PCIE_S_CLK),
+	CCU_DIV_RST_MAP(CCU_AXI_USB_RST, CCU_AXI_USB_CLK),
+	CCU_DIV_RST_MAP(CCU_AXI_HWA_RST, CCU_AXI_HWA_CLK),
+	CCU_DIV_RST_MAP(CCU_AXI_SRAM_RST, CCU_AXI_SRAM_CLK)
+};
+
+/*
+ * APB-bus clock is marked as critical since it's a main communication bus
+ * for the SoC devices registers IO-operations.
+ */
+static const struct ccu_div_info sys_info[] = {
+	CCU_DIV_VAR_INFO(CCU_SYS_SATA_REF_CLK, "sys_sata_ref_clk",
+			 "sata_clk", CCU_SYS_SATA_REF_BASE, 4,
+			 CLK_SET_RATE_GATE,
+			 CCU_DIV_SKIP_ONE | CCU_DIV_LOCK_SHIFTED |
+			 CCU_DIV_RESET_DOMAIN),
+	CCU_DIV_VAR_INFO(CCU_SYS_APB_CLK, "sys_apb_clk",
+			 "pcie_clk", CCU_SYS_APB_BASE, 5,
+			 CLK_IS_CRITICAL, CCU_DIV_RESET_DOMAIN),
+	CCU_DIV_GATE_INFO(CCU_SYS_GMAC0_TX_CLK, "sys_gmac0_tx_clk",
+			  "eth_clk", CCU_SYS_GMAC0_BASE, 5),
+	CCU_DIV_FIXED_INFO(CCU_SYS_GMAC0_PTP_CLK, "sys_gmac0_ptp_clk",
+			   "eth_clk", 10),
+	CCU_DIV_GATE_INFO(CCU_SYS_GMAC1_TX_CLK, "sys_gmac1_tx_clk",
+			  "eth_clk", CCU_SYS_GMAC1_BASE, 5),
+	CCU_DIV_FIXED_INFO(CCU_SYS_GMAC1_PTP_CLK, "sys_gmac1_ptp_clk",
+			   "eth_clk", 10),
+	CCU_DIV_GATE_INFO(CCU_SYS_XGMAC_REF_CLK, "sys_xgmac_ref_clk",
+			  "eth_clk", CCU_SYS_XGMAC_BASE, 8),
+	CCU_DIV_FIXED_INFO(CCU_SYS_XGMAC_PTP_CLK, "sys_xgmac_ptp_clk",
+			   "eth_clk", 10),
+	CCU_DIV_GATE_INFO(CCU_SYS_USB_CLK, "sys_usb_clk",
+			  "eth_clk", CCU_SYS_USB_BASE, 10),
+	CCU_DIV_VAR_INFO(CCU_SYS_PVT_CLK, "sys_pvt_clk",
+			 "ref_clk", CCU_SYS_PVT_BASE, 5,
+			 CLK_SET_RATE_GATE, 0),
+	CCU_DIV_VAR_INFO(CCU_SYS_HWA_CLK, "sys_hwa_clk",
+			 "sata_clk", CCU_SYS_HWA_BASE, 4,
+			 CLK_SET_RATE_GATE, 0),
+	CCU_DIV_VAR_INFO(CCU_SYS_UART_CLK, "sys_uart_clk",
+			 "eth_clk", CCU_SYS_UART_BASE, 17,
+			 CLK_SET_RATE_GATE, 0),
+	CCU_DIV_FIXED_INFO(CCU_SYS_I2C1_CLK, "sys_i2c1_clk",
+			   "eth_clk", 10),
+	CCU_DIV_FIXED_INFO(CCU_SYS_I2C2_CLK, "sys_i2c2_clk",
+			   "eth_clk", 10),
+	CCU_DIV_FIXED_INFO(CCU_SYS_GPIO_CLK, "sys_gpio_clk",
+			   "ref_clk", 25),
+	CCU_DIV_VAR_INFO(CCU_SYS_TIMER0_CLK, "sys_timer0_clk",
+			 "ref_clk", CCU_SYS_TIMER0_BASE, 17,
+			 CLK_SET_RATE_GATE, 0),
+	CCU_DIV_VAR_INFO(CCU_SYS_TIMER1_CLK, "sys_timer1_clk",
+			 "ref_clk", CCU_SYS_TIMER1_BASE, 17,
+			 CLK_SET_RATE_GATE, 0),
+	CCU_DIV_VAR_INFO(CCU_SYS_TIMER2_CLK, "sys_timer2_clk",
+			 "ref_clk", CCU_SYS_TIMER2_BASE, 17,
+			 CLK_SET_RATE_GATE, 0),
+	CCU_DIV_VAR_INFO(CCU_SYS_WDT_CLK, "sys_wdt_clk",
+			 "eth_clk", CCU_SYS_WDT_BASE, 17,
+			 CLK_SET_RATE_GATE, CCU_DIV_SKIP_ONE_TO_THREE)
+};
+
+static const struct ccu_div_rst_map sys_rst_map[] = {
+	CCU_DIV_RST_MAP(CCU_SYS_SATA_REF_RST, CCU_SYS_SATA_REF_CLK),
+	CCU_DIV_RST_MAP(CCU_SYS_APB_RST, CCU_SYS_APB_CLK),
+};
+
+static struct ccu_div *ccu_div_find_desc(struct ccu_div_data *data,
+					 unsigned int clk_id)
+{
+	struct ccu_div *div;
+	int idx;
+
+	for (idx = 0; idx < data->divs_num; ++idx) {
+		div = data->divs[idx];
+		if (div && div->id == clk_id)
+			return div;
+	}
+
+	return ERR_PTR(-EINVAL);
+}
+
+static int ccu_div_reset(struct reset_controller_dev *rcdev,
+			 unsigned long rst_id)
+{
+	struct ccu_div_data *data = to_ccu_div_data(rcdev);
+	const struct ccu_div_rst_map *map;
+	struct ccu_div *div;
+	int idx, ret;
+
+	for (idx = 0, map = data->rst_map; idx < data->rst_num; ++idx, ++map) {
+		if (map->rst_id == rst_id)
+			break;
+	}
+	if (idx == data->rst_num) {
+		pr_err("Invalid reset ID %lu specified\n", rst_id);
+		return -EINVAL;
+	}
+
+	div = ccu_div_find_desc(data, map->clk_id);
+	if (IS_ERR(div)) {
+		pr_err("Invalid clock ID %d in mapping\n", map->clk_id);
+		return PTR_ERR(div);
+	}
+
+	ret = ccu_div_reset_domain(div);
+	if (ret) {
+		pr_err("Reset isn't supported by divider %s\n",
+			clk_hw_get_name(ccu_div_get_clk_hw(div)));
+	}
+
+	return ret;
+}
+
+static const struct reset_control_ops ccu_div_rst_ops = {
+	.reset = ccu_div_reset,
+};
+
+static struct ccu_div_data *ccu_div_create_data(struct device_node *np)
+{
+	struct ccu_div_data *data;
+	int ret;
+
+	data = kzalloc(sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return ERR_PTR(-ENOMEM);
+
+	data->np = np;
+	if (of_device_is_compatible(np, "baikal,bt1-ccu-axi")) {
+		data->divs_num = ARRAY_SIZE(axi_info);
+		data->divs_info = axi_info;
+		data->rst_num = ARRAY_SIZE(axi_rst_map);
+		data->rst_map = axi_rst_map;
+	} else if (of_device_is_compatible(np, "baikal,bt1-ccu-sys")) {
+		data->divs_num = ARRAY_SIZE(sys_info);
+		data->divs_info = sys_info;
+		data->rst_num = ARRAY_SIZE(sys_rst_map);
+		data->rst_map = sys_rst_map;
+	} else {
+		pr_err("Uncompatible DT node '%s' specified\n",
+			of_node_full_name(np));
+		ret = -EINVAL;
+		goto err_kfree_data;
+	}
+
+	data->divs = kcalloc(data->divs_num, sizeof(*data->divs), GFP_KERNEL);
+	if (!data->divs) {
+		ret = -ENOMEM;
+		goto err_kfree_data;
+	}
+
+	return data;
+
+err_kfree_data:
+	kfree(data);
+
+	return ERR_PTR(ret);
+}
+
+static void ccu_div_free_data(struct ccu_div_data *data)
+{
+	kfree(data->divs);
+
+	kfree(data);
+}
+
+static int ccu_div_find_sys_regs(struct ccu_div_data *data)
+{
+	data->sys_regs = syscon_node_to_regmap(data->np->parent);
+	if (IS_ERR(data->sys_regs)) {
+		pr_err("Failed to find syscon regs for '%s'\n",
+			of_node_full_name(data->np));
+		return PTR_ERR(data->sys_regs);
+	}
+
+	return 0;
+}
+
+static struct clk_hw *ccu_div_of_clk_hw_get(struct of_phandle_args *clkspec,
+					    void *priv)
+{
+	struct ccu_div_data *data = priv;
+	struct ccu_div *div;
+	unsigned int clk_id;
+
+	clk_id = clkspec->args[0];
+	div = ccu_div_find_desc(data, clk_id);
+	if (IS_ERR(div)) {
+		pr_info("Invalid clock ID %d specified\n", clk_id);
+		return ERR_CAST(div);
+	}
+
+	return ccu_div_get_clk_hw(div);
+}
+
+static int ccu_div_clk_register(struct ccu_div_data *data)
+{
+	int idx, ret;
+
+	for (idx = 0; idx < data->divs_num; ++idx) {
+		const struct ccu_div_info *info = &data->divs_info[idx];
+		struct ccu_div_init_data init = {0};
+
+		init.id = info->id;
+		init.name = info->name;
+		init.parent_name = info->parent_name;
+		init.np = data->np;
+		init.type = info->type;
+		init.flags = info->flags;
+		init.features = info->features;
+
+		if (init.type == CCU_DIV_VAR) {
+			init.base = info->base;
+			init.sys_regs = data->sys_regs;
+			init.width = info->width;
+		} else if (init.type == CCU_DIV_GATE) {
+			init.base = info->base;
+			init.sys_regs = data->sys_regs;
+			init.divider = info->divider;
+		} else {
+			init.divider = info->divider;
+		}
+
+		data->divs[idx] = ccu_div_hw_register(&init);
+		if (IS_ERR(data->divs[idx])) {
+			ret = PTR_ERR(data->divs[idx]);
+			pr_err("Couldn't register divider '%s' hw\n",
+				init.name);
+			goto err_hw_unregister;
+		}
+	}
+
+	ret = of_clk_add_hw_provider(data->np, ccu_div_of_clk_hw_get, data);
+	if (ret) {
+		pr_err("Couldn't register dividers '%s' clock provider\n",
+			of_node_full_name(data->np));
+		goto err_hw_unregister;
+	}
+
+	return 0;
+
+err_hw_unregister:
+	for (--idx; idx >= 0; --idx)
+		ccu_div_hw_unregister(data->divs[idx]);
+
+	return ret;
+}
+
+static void ccu_div_clk_unregister(struct ccu_div_data *data)
+{
+	int idx;
+
+	of_clk_del_provider(data->np);
+
+	for (idx = 0; idx < data->divs_num; ++idx)
+		ccu_div_hw_unregister(data->divs[idx]);
+}
+
+static int ccu_div_rst_register(struct ccu_div_data *data)
+{
+	int ret;
+
+	data->rcdev.ops = &ccu_div_rst_ops;
+	data->rcdev.of_node = data->np;
+	data->rcdev.nr_resets = data->rst_num;
+
+	ret = reset_controller_register(&data->rcdev);
+	if (ret)
+		pr_err("Couldn't register divider '%s' reset controller\n",
+			of_node_full_name(data->np));
+
+	return ret;
+}
+
+static void ccu_div_init(struct device_node *np)
+{
+	struct ccu_div_data *data;
+	int ret;
+
+	data = ccu_div_create_data(np);
+	if (IS_ERR(data))
+		return;
+
+	ret = ccu_div_find_sys_regs(data);
+	if (ret)
+		goto err_free_data;
+
+	ret = ccu_div_clk_register(data);
+	if (ret)
+		goto err_free_data;
+
+	ret = ccu_div_rst_register(data);
+	if (ret)
+		goto err_clk_unregister;
+
+	return;
+
+err_clk_unregister:
+	ccu_div_clk_unregister(data);
+
+err_free_data:
+	ccu_div_free_data(data);
+}
+
+CLK_OF_DECLARE(ccu_axi, "baikal,bt1-ccu-axi", ccu_div_init);
+CLK_OF_DECLARE(ccu_sys, "baikal,bt1-ccu-sys", ccu_div_init);