staging: Add Xilinx Clocking Wizard driver

Add a driver for the Xilinx Clocking Wizard soft IP. The clocking wizard
provides an AXI interface to dynamically reconfigure the clocking
resources of Xilinx FPGAs.

Signed-off-by: Soren Brinkmann <[e-mail]>
Acked-by: Laurent Pinchart <[e-mail]>
Signed-off-by: Greg Kroah-Hartman <[e-mail]>

drivers/staging/Kconfig

···
 
 source "drivers/staging/unisys/Kconfig"
 
+source "drivers/staging/clocking-wizard/Kconfig"
+
 endif # STAGING

drivers/staging/Makefile

···
 obj-$(CONFIG_GS_FPGABOOT)	+= gs_fpgaboot/
 obj-$(CONFIG_CRYPTO_SKEIN)	+= skein/
 obj-$(CONFIG_UNISYSSPAR)	+= unisys/
+obj-$(CONFIG_COMMON_CLK_XLNX_CLKWZRD)	+= clocking-wizard/

drivers/staging/clocking-wizard/Kconfig

···
+#
+# Xilinx Clocking Wizard Driver
+#
+
+config COMMON_CLK_XLNX_CLKWZRD
+	tristate "Xilinx Clocking Wizard"
+	depends on COMMON_CLK && OF
+	---help---
+	  Support for the Xilinx Clocking Wizard IP core clock generator.

drivers/staging/clocking-wizard/Makefile

···
+obj-$(CONFIG_COMMON_CLK_XLNX_CLKWZRD)	+= clk-xlnx-clock-wizard.o

drivers/staging/clocking-wizard/TODO

···
+TODO:
+	- support for fractional multiplier
+	- support for fractional divider (output 0 only)
+	- support for set_rate() operations (may benefit from Stephen Boyd's
+	  refactoring of the clk primitives: https://lkml.org/lkml/2014/9/5/766)
+	- review arithmetic
+	  - overflow after multiplication?
+	  - maximize accuracy before divisions
+
+Patches to:
+	Greg Kroah-Hartman <[e-mail]>
+	Sören Brinkmann <[e-mail]>

drivers/staging/clocking-wizard/clk-xlnx-clock-wizard.c

···
+/*
+ * Xilinx 'Clocking Wizard' driver
+ *
+ *  Copyright (C) 2013 - 2014 Xilinx
+ *
+ *  Sören Brinkmann <[e-mail]>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License v2 as published by
+ * the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <linux/platform_device.h>
+#include <linux/clk-provider.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/module.h>
+#include <linux/err.h>
+
+#define WZRD_NUM_OUTPUTS	7
+#define WZRD_ACLK_MAX_FREQ	250000000UL
+
+#define WZRD_CLK_CFG_REG(n)	(0x200 + 4 * n)
+
+#define WZRD_CLkOUT0_FRAC_EN	BIT(18)
+#define WZRD_CLkFBOUT_FRAC_EN	BIT(26)
+
+#define WZRD_CLKFBOUT_MULT_SHIFT	8
+#define WZRD_CLKFBOUT_MULT_MASK		(0xff << WZRD_CLKFBOUT_MULT_SHIFT)
+#define WZRD_DIVCLK_DIVIDE_SHIFT	0
+#define WZRD_DIVCLK_DIVIDE_MASK		(0xff << WZRD_DIVCLK_DIVIDE_SHIFT)
+#define WZRD_CLKOUT_DIVIDE_SHIFT	0
+#define WZRD_CLKOUT_DIVIDE_MASK		(0xff << WZRD_DIVCLK_DIVIDE_SHIFT)
+
+enum clk_wzrd_int_clks {
+	wzrd_clk_mul,
+	wzrd_clk_mul_div,
+	wzrd_clk_int_max
+};
+
+/**
+ * struct clk_wzrd:
+ * @clk_data:		Clock data
+ * @nb:			Notifier block
+ * @base:		Memory base
+ * @clk_in1:		Handle to input clock 'clk_in1'
+ * @axi_clk:		Handle to input clock 's_axi_aclk'
+ * @clks_internal:	Internal clocks
+ * @clkout:		Output clocks
+ * @speed_grade:	Speed grade of the device
+ * @suspended:		Flag indicating power state of the device
+ */
+struct clk_wzrd {
+	struct clk_onecell_data clk_data;
+	struct notifier_block nb;
+	void __iomem *base;
+	struct clk *clk_in1;
+	struct clk *axi_clk;
+	struct clk *clks_internal[wzrd_clk_int_max];
+	struct clk *clkout[WZRD_NUM_OUTPUTS];
+	int speed_grade;
+	bool suspended;
+};
+#define to_clk_wzrd(_nb) container_of(_nb, struct clk_wzrd, nb)
+
+/* maximum frequencies for input/output clocks per speed grade */
+static const unsigned long clk_wzrd_max_freq[] = {
+	800000000UL,
+	933000000UL,
+	1066000000UL
+};
+
+static int clk_wzrd_clk_notifier(struct notifier_block *nb, unsigned long event,
+				 void *data)
+{
+	unsigned long max;
+	struct clk_notifier_data *ndata = data;
+	struct clk_wzrd *clk_wzrd = to_clk_wzrd(nb);
+
+	if (clk_wzrd->suspended)
+		return NOTIFY_OK;
+
+	if (ndata->clk == clk_wzrd->clk_in1)
+		max = clk_wzrd_max_freq[clk_wzrd->speed_grade - 1];
+	if (ndata->clk == clk_wzrd->axi_clk)
+		max = WZRD_ACLK_MAX_FREQ;
+
+	switch (event) {
+	case PRE_RATE_CHANGE:
+		if (ndata->new_rate > max)
+			return NOTIFY_BAD;
+		return NOTIFY_OK;
+	case POST_RATE_CHANGE:
+	case ABORT_RATE_CHANGE:
+	default:
+		return NOTIFY_DONE;
+	}
+}
+
+static int __maybe_unused clk_wzrd_suspend(struct device *dev)
+{
+	struct clk_wzrd *clk_wzrd = dev_get_drvdata(dev);
+
+	clk_disable_unprepare(clk_wzrd->axi_clk);
+	clk_wzrd->suspended = true;
+
+	return 0;
+}
+
+static int __maybe_unused clk_wzrd_resume(struct device *dev)
+{
+	int ret;
+	struct clk_wzrd *clk_wzrd = dev_get_drvdata(dev);
+
+	ret = clk_prepare_enable(clk_wzrd->axi_clk);
+	if (ret) {
+		dev_err(dev, "unable to enable s_axi_aclk\n");
+		return ret;
+	}
+
+	clk_wzrd->suspended = false;
+
+	return 0;
+}
+
+static SIMPLE_DEV_PM_OPS(clk_wzrd_dev_pm_ops, clk_wzrd_suspend,
+			 clk_wzrd_resume);
+
+static int clk_wzrd_probe(struct platform_device *pdev)
+{
+	int i, ret;
+	u32 reg;
+	unsigned long rate;
+	const char *clk_name;
+	struct clk_wzrd *clk_wzrd;
+	struct resource *mem;
+	struct device_node *np = pdev->dev.of_node;
+
+	clk_wzrd = devm_kzalloc(&pdev->dev, sizeof(*clk_wzrd), GFP_KERNEL);
+	if (!clk_wzrd)
+		return -ENOMEM;
+	platform_set_drvdata(pdev, clk_wzrd);
+
+	mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	clk_wzrd->base = devm_ioremap_resource(&pdev->dev, mem);
+	if (IS_ERR(clk_wzrd->base))
+		return PTR_ERR(clk_wzrd->base);
+
+	ret = of_property_read_u32(np, "speed-grade", &clk_wzrd->speed_grade);
+	if (!ret) {
+		if (clk_wzrd->speed_grade < 1 || clk_wzrd->speed_grade > 3) {
+			dev_warn(&pdev->dev, "invalid speed grade '%d'\n",
+				 clk_wzrd->speed_grade);
+			clk_wzrd->speed_grade = 0;
+		}
+	}
+
+	clk_wzrd->clk_in1 = devm_clk_get(&pdev->dev, "clk_in1");
+	if (IS_ERR(clk_wzrd->clk_in1)) {
+		if (clk_wzrd->clk_in1 != ERR_PTR(-EPROBE_DEFER))
+			dev_err(&pdev->dev, "clk_in1 not found\n");
+		return PTR_ERR(clk_wzrd->clk_in1);
+	}
+
+	clk_wzrd->axi_clk = devm_clk_get(&pdev->dev, "s_axi_aclk");
+	if (IS_ERR(clk_wzrd->axi_clk)) {
+		if (clk_wzrd->axi_clk != ERR_PTR(-EPROBE_DEFER))
+			dev_err(&pdev->dev, "s_axi_aclk not found\n");
+		return PTR_ERR(clk_wzrd->axi_clk);
+	}
+	ret = clk_prepare_enable(clk_wzrd->axi_clk);
+	if (ret) {
+		dev_err(&pdev->dev, "enabling s_axi_aclk failed\n");
+		return ret;
+	}
+	rate = clk_get_rate(clk_wzrd->axi_clk);
+	if (rate > WZRD_ACLK_MAX_FREQ) {
+		dev_err(&pdev->dev, "s_axi_aclk frequency (%lu) too high\n",
+			rate);
+		ret = -EINVAL;
+		goto err_disable_clk;
+	}
+
+	/* we don't support fractional div/mul yet */
+	reg = readl(clk_wzrd->base + WZRD_CLK_CFG_REG(0)) &
+		    WZRD_CLkFBOUT_FRAC_EN;
+	reg |= readl(clk_wzrd->base + WZRD_CLK_CFG_REG(2)) &
+		     WZRD_CLkOUT0_FRAC_EN;
+	if (reg)
+		dev_warn(&pdev->dev, "fractional div/mul not supported\n");
+
+	/* register multiplier */
+	reg = (readl(clk_wzrd->base + WZRD_CLK_CFG_REG(0)) &
+		     WZRD_CLKFBOUT_MULT_MASK) >> WZRD_CLKFBOUT_MULT_SHIFT;
+	clk_name = kasprintf(GFP_KERNEL, "%s_mul", dev_name(&pdev->dev));
+	if (!clk_name) {
+		ret = -ENOMEM;
+		goto err_disable_clk;
+	}
+	clk_wzrd->clks_internal[wzrd_clk_mul] = clk_register_fixed_factor(
+			&pdev->dev, clk_name,
+			__clk_get_name(clk_wzrd->clk_in1),
+			0, reg, 1);
+	kfree(clk_name);
+	if (IS_ERR(clk_wzrd->clks_internal[wzrd_clk_mul])) {
+		dev_err(&pdev->dev, "unable to register fixed-factor clock\n");
+		ret = PTR_ERR(clk_wzrd->clks_internal[wzrd_clk_mul]);
+		goto err_disable_clk;
+	}
+
+	/* register div */
+	reg = (readl(clk_wzrd->base + WZRD_CLK_CFG_REG(0)) &
+			WZRD_DIVCLK_DIVIDE_MASK) >> WZRD_DIVCLK_DIVIDE_SHIFT;
+	clk_name = kasprintf(GFP_KERNEL, "%s_mul_div", dev_name(&pdev->dev));
+	clk_wzrd->clks_internal[wzrd_clk_mul_div] = clk_register_fixed_factor(
+			&pdev->dev, clk_name,
+			__clk_get_name(clk_wzrd->clks_internal[wzrd_clk_mul]),
+			0, 1, reg);
+	if (IS_ERR(clk_wzrd->clks_internal[wzrd_clk_mul_div])) {
+		dev_err(&pdev->dev, "unable to register divider clock\n");
+		ret = PTR_ERR(clk_wzrd->clks_internal[wzrd_clk_mul_div]);
+		goto err_rm_int_clk;
+	}
+
+	/* register div per output */
+	for (i = WZRD_NUM_OUTPUTS - 1; i >= 0 ; i--) {
+		const char *clkout_name;
+		if (of_property_read_string_index(np, "clock-output-names", i,
+						  &clkout_name)) {
+			dev_err(&pdev->dev,
+				"clock output name not specified\n");
+			ret = -EINVAL;
+			goto err_rm_int_clks;
+		}
+		reg = readl(clk_wzrd->base + WZRD_CLK_CFG_REG(2) + i * 12);
+		reg &= WZRD_CLKOUT_DIVIDE_MASK;
+		reg >>= WZRD_CLKOUT_DIVIDE_SHIFT;
+		clk_wzrd->clkout[i] = clk_register_fixed_factor(&pdev->dev,
+				clkout_name, clk_name, 0, 1, reg);
+		if (IS_ERR(clk_wzrd->clkout[i])) {
+			int j;
+			for (j = i + 1; j < WZRD_NUM_OUTPUTS; j++)
+				clk_unregister(clk_wzrd->clkout[j]);
+			dev_err(&pdev->dev,
+				"unable to register divider clock\n");
+			ret = PTR_ERR(clk_wzrd->clkout[i]);
+			goto err_rm_int_clks;
+		}
+	}
+
+	kfree(clk_name);
+
+	clk_wzrd->clk_data.clks = clk_wzrd->clkout;
+	clk_wzrd->clk_data.clk_num = ARRAY_SIZE(clk_wzrd->clkout);
+	of_clk_add_provider(np, of_clk_src_onecell_get, &clk_wzrd->clk_data);
+
+	if (clk_wzrd->speed_grade) {
+		clk_wzrd->nb.notifier_call = clk_wzrd_clk_notifier;
+
+		ret = clk_notifier_register(clk_wzrd->clk_in1,
+					    &clk_wzrd->nb);
+		if (ret)
+			dev_warn(&pdev->dev,
+				 "unable to register clock notifier\n");
+
+		ret = clk_notifier_register(clk_wzrd->axi_clk, &clk_wzrd->nb);
+		if (ret)
+			dev_warn(&pdev->dev,
+				 "unable to register clock notifier\n");
+	}
+
+	return 0;
+
+err_rm_int_clks:
+	clk_unregister(clk_wzrd->clks_internal[1]);
+err_rm_int_clk:
+	kfree(clk_name);
+	clk_unregister(clk_wzrd->clks_internal[0]);
+err_disable_clk:
+	clk_disable_unprepare(clk_wzrd->axi_clk);
+
+	return ret;
+}
+
+static int clk_wzrd_remove(struct platform_device *pdev)
+{
+	int i;
+	struct clk_wzrd *clk_wzrd = platform_get_drvdata(pdev);
+
+	of_clk_del_provider(pdev->dev.of_node);
+
+	for (i = 0; i < WZRD_NUM_OUTPUTS; i++)
+		clk_unregister(clk_wzrd->clkout[i]);
+	for (i = 0; i < wzrd_clk_int_max; i++)
+		clk_unregister(clk_wzrd->clks_internal[i]);
+
+	if (clk_wzrd->speed_grade) {
+		clk_notifier_unregister(clk_wzrd->axi_clk, &clk_wzrd->nb);
+		clk_notifier_unregister(clk_wzrd->clk_in1, &clk_wzrd->nb);
+	}
+
+	clk_disable_unprepare(clk_wzrd->axi_clk);
+
+	return 0;
+}
+
+static const struct of_device_id clk_wzrd_ids[] = {
+	{ .compatible = "xlnx,clocking-wizard" },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, clk_wzrd_ids);
+
+static struct platform_driver clk_wzrd_driver = {
+	.driver = {
+		.name = "clk-wizard",
+		.of_match_table = clk_wzrd_ids,
+		.pm = &clk_wzrd_dev_pm_ops,
+	},
+	.probe = clk_wzrd_probe,
+	.remove = clk_wzrd_remove,
+};
+module_platform_driver(clk_wzrd_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Soeren Brinkmann <[e-mail]");
+MODULE_DESCRIPTION("Driver for the Xilinx Clocking Wizard IP core");

drivers/staging/clocking-wizard/dt-binding.txt

···
+Binding for Xilinx Clocking Wizard IP Core
+
+This binding uses the common clock binding[1]. Details about the devices can be
+found in the product guide[2].
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+[2] Clocking Wizard Product Guide
+http://www.xilinx.com/support/documentation/ip_documentation/clk_wiz/v5_1/pg065-clk-wiz.pdf
+
+Required properties:
+ - compatible: Must be 'xlnx,clocking-wizard'
+ - reg: Base and size of the cores register space
+ - clocks: Handle to input clock
+ - clock-names: Tuple containing 'clk_in1' and 's_axi_aclk'
+ - clock-output-names: Names for the output clocks
+
+Optional properties:
+ - speed-grade: Speed grade of the device (valid values are 1..3)
+
+Example:
+	clock-generator@40040000 {
+		reg = <0x40040000 0x1000>;
+		compatible = "xlnx,clocking-wizard";
+		speed-grade = <1>;
+		clock-names = "clk_in1", "s_axi_aclk";
+		clocks = <&clkc 15>, <&clkc 15>;
+		clock-output-names = "clk_out0", "clk_out1", "clk_out2",
+				     "clk_out3", "clk_out4", "clk_out5",
+				     "clk_out6", "clk_out7";
+	};