[PATCH v2] clk: Add axi-clkgen driver

From: Lars-Peter Clausen
Date: Wed Jan 23 2013 - 09:03:55 EST

This driver adds support for the AXI clkgen pcore to the common clock framework.
The AXI clkgen pcore is a AXI front-end to the MMCM_ADV frequency synthesizer
commonly found in Xilinx FPGAs.

The AXI clkgen pcore is used in Analog Devices' reference designs targeting
Xilinx FPGAs.

Signed-off-by: Lars-Peter Clausen <lars@xxxxxxxxxx>

---
Changes since v1:
* Fix error in the filter coef lookup table
* Use unsigend long long arithmetic to avoid overflow when calculating the
current clock frequency.
* Use readl/writel instead of ioread32/iowrite32
---
.../devicetree/bindings/clock/axi-clkgen.txt | 22 ++
drivers/clk/Kconfig | 8 +
drivers/clk/Makefile | 1 +
drivers/clk/clk-axi-clkgen.c | 331 +++++++++++++++++++++
4 files changed, 362 insertions(+)
create mode 100644 Documentation/devicetree/bindings/clock/axi-clkgen.txt
create mode 100644 drivers/clk/clk-axi-clkgen.c

diff --git a/Documentation/devicetree/bindings/clock/axi-clkgen.txt b/Documentation/devicetree/bindings/clock/axi-clkgen.txt
new file mode 100644
index 0000000..028b493
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/axi-clkgen.txt
@@ -0,0 +1,22 @@
+Binding for the axi-clkgen clock generator
+
+This binding uses the common clock binding[1].
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+Required properties:
+- compatible : shall be "adi,axi-clkgen".
+- #clock-cells : from common clock binding; Should always be set to 0.
+- reg : Address and length of the axi-clkgen register set.
+- clocks : Phandle and clock specifier for the parent clock.
+
+Optional properties:
+- clock-output-names : From common clock binding.
+
+Example:
+ clock@0xff000000 {
+ compatible = "adi,axi-clkgen";
+ #clock-cells = <0>;
+ reg = <0xff000000 0x1000>;
+ clocks = <&osc 1>;
+ };
diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index a47e6ee..36df007 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -63,6 +63,14 @@ config CLK_TWL6040
McPDM. McPDM module is using the external bit clock on the McPDM bus
as functional clock.

+config COMMON_CLK_AXI_CLKGEN
+ tristate "AXI clkgen driver"
+ depends on ARCH_ZYNQ || MICROBLAZE
+ help
+ ---help---
+ Support for the Analog Device axi-clkgen pcore clock generator for Xilinx
+ FPGAs. It is commonly used in Analog Devices reference designs.
+
endmenu

source "drivers/clk/mvebu/Kconfig"
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index ee90e87..a3617b2 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -24,6 +24,7 @@ obj-$(CONFIG_ARCH_SUNXI) += clk-sunxi.o
obj-$(CONFIG_ARCH_ZYNQ) += clk-zynq.o

# Chip specific
+obj-$(CONFIG_COMMON_CLK_AXI_CLKGEN) += clk-axi-clkgen.o
obj-$(CONFIG_COMMON_CLK_WM831X) += clk-wm831x.o
obj-$(CONFIG_COMMON_CLK_MAX77686) += clk-max77686.o
obj-$(CONFIG_CLK_TWL6040) += clk-twl6040.o
diff --git a/drivers/clk/clk-axi-clkgen.c b/drivers/clk/clk-axi-clkgen.c
new file mode 100644
index 0000000..a956ed8
--- /dev/null
+++ b/drivers/clk/clk-axi-clkgen.c
@@ -0,0 +1,331 @@
+/*
+ * AXI clkgen driver
+ *
+ * Copyright 2012-2013 Analog Device Inc.
+ * Author: Lars-Peter Clausen <lars@xxxxxxxxxx>
+ *
+ * Licensed under the GPL-2.
+ *
+ */
+
+#include <linux/platform_device.h>
+#include <linux/clk-provider.h>
+#include <linux/clk.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/module.h>
+#include <linux/err.h>
+
+#define AXI_CLKGEN_REG_UPDATE_ENABLE 0x04
+#define AXI_CLKGEN_REG_CLK_OUT1 0x08
+#define AXI_CLKGEN_REG_CLK_OUT2 0x0c
+#define AXI_CLKGEN_REG_CLK_DIV 0x10
+#define AXI_CLKGEN_REG_CLK_FB1 0x14
+#define AXI_CLKGEN_REG_CLK_FB2 0x18
+#define AXI_CLKGEN_REG_LOCK1 0x1c
+#define AXI_CLKGEN_REG_LOCK2 0x20
+#define AXI_CLKGEN_REG_LOCK3 0x24
+#define AXI_CLKGEN_REG_FILTER1 0x28
+#define AXI_CLKGEN_REG_FILTER2 0x2c
+
+struct axi_clkgen {
+ void __iomem *base;
+ struct clk_hw clk_hw;
+};
+
+static uint32_t axi_clkgen_lookup_filter(unsigned int m)
+{
+ switch (m) {
+ case 0:
+ return 0x01001990;
+ case 1:
+ return 0x01001190;
+ case 2:
+ return 0x01009890;
+ case 3:
+ return 0x01001890;
+ case 4:
+ return 0x01008890;
+ case 5 ... 8:
+ return 0x01009090;
+ case 9 ... 11:
+ return 0x01000890;
+ case 12:
+ return 0x08009090;
+ case 13 ... 22:
+ return 0x01001090;
+ case 23 ... 36:
+ return 0x01008090;
+ case 37 ... 46:
+ return 0x08001090;
+ default:
+ return 0x08008090;
+ }
+}
+
+static const uint32_t axi_clkgen_lock_table[] = {
+ 0x060603e8, 0x060603e8, 0x080803e8, 0x0b0b03e8,
+ 0x0e0e03e8, 0x111103e8, 0x131303e8, 0x161603e8,
+ 0x191903e8, 0x1c1c03e8, 0x1f1f0384, 0x1f1f0339,
+ 0x1f1f02ee, 0x1f1f02bc, 0x1f1f028a, 0x1f1f0271,
+ 0x1f1f023f, 0x1f1f0226, 0x1f1f020d, 0x1f1f01f4,
+ 0x1f1f01db, 0x1f1f01c2, 0x1f1f01a9, 0x1f1f0190,
+ 0x1f1f0190, 0x1f1f0177, 0x1f1f015e, 0x1f1f015e,
+ 0x1f1f0145, 0x1f1f0145, 0x1f1f012c, 0x1f1f012c,
+ 0x1f1f012c, 0x1f1f0113, 0x1f1f0113, 0x1f1f0113,
+};
+
+static uint32_t axi_clkgen_lookup_lock(unsigned int m)
+{
+ if (m < ARRAY_SIZE(axi_clkgen_lock_table))
+ return axi_clkgen_lock_table[m];
+ return 0x1f1f00fa;
+}
+
+static const unsigned int fpfd_min = 10000;
+static const unsigned int fpfd_max = 300000;
+static const unsigned int fvco_min = 600000;
+static const unsigned int fvco_max = 1200000;
+
+static void axi_clkgen_calc_params(unsigned long fin, unsigned long fout,
+ unsigned int *best_d, unsigned int *best_m, unsigned int *best_dout)
+{
+ unsigned long d, d_min, d_max, _d_min, _d_max;
+ unsigned long m, m_min, m_max;
+ unsigned long f, dout, best_f, fvco;
+
+ fin /= 1000;
+ fout /= 1000;
+
+ best_f = UINT_MAX;
+ *best_d = 0;
+ *best_m = 0;
+ *best_dout = 0;
+
+ d_min = max_t(unsigned long, DIV_ROUND_UP(fin, fpfd_max), 1);
+ d_max = min_t(unsigned long, fin / fpfd_min, 80);
+
+ m_min = max_t(unsigned long, DIV_ROUND_UP(fvco_min, fin) * d_min, 1);
+ m_max = min_t(unsigned long, fvco_max * d_max / fin, 64);
+
+ for (m = m_min; m <= m_max; m++) {
+ _d_min = max(d_min, DIV_ROUND_UP(fin * m, fvco_max));
+ _d_max = min(d_max, fin * m / fvco_min);
+
+ for (d = _d_min; d <= _d_max; d++) {
+ fvco = fin * m / d;
+
+ dout = DIV_ROUND_CLOSEST(fvco, fout);
+ dout = clamp_t(unsigned long, dout, 1, 128);
+ f = fvco / dout;
+ if (abs(f - fout) < abs(best_f - fout)) {
+ best_f = f;
+ *best_d = d;
+ *best_m = m;
+ *best_dout = dout;
+ if (best_f == fout)
+ return;
+ }
+ }
+ }
+}
+
+static void axi_clkgen_calc_clk_params(unsigned int divider, unsigned int *low,
+ unsigned int *high, unsigned int *edge, unsigned int *nocount)
+{
+ if (divider == 1)
+ *nocount = 1;
+ else
+ *nocount = 0;
+
+ *high = divider / 2;
+ *edge = divider % 2;
+ *low = divider - *high;
+}
+
+static void axi_clkgen_write(struct axi_clkgen *axi_clkgen,
+ unsigned int reg, unsigned int val)
+{
+ writel(val, axi_clkgen->base + reg);
+}
+
+static void axi_clkgen_read(struct axi_clkgen *axi_clkgen,
+ unsigned int reg, unsigned int *val)
+{
+ *val = readl(axi_clkgen->base + reg);
+}
+
+static struct axi_clkgen *clk_hw_to_axi_clkgen(struct clk_hw *clk_hw)
+{
+ return container_of(clk_hw, struct axi_clkgen, clk_hw);
+}
+
+static int axi_clkgen_set_rate(struct clk_hw *clk_hw,
+ unsigned long rate, unsigned long parent_rate)
+{
+ struct axi_clkgen *axi_clkgen = clk_hw_to_axi_clkgen(clk_hw);
+ unsigned int d, m, dout;
+ unsigned int nocount;
+ unsigned int high;
+ unsigned int edge;
+ unsigned int low;
+ uint32_t filter;
+ uint32_t lock;
+
+ if (parent_rate == 0 || rate == 0)
+ return -EINVAL;
+
+ axi_clkgen_calc_params(parent_rate, rate, &d, &m, &dout);
+
+ if (d == 0 || dout == 0 || m == 0)
+ return -EINVAL;
+
+ filter = axi_clkgen_lookup_filter(m - 1);
+ lock = axi_clkgen_lookup_lock(m - 1);
+
+ axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_UPDATE_ENABLE, 0);
+
+ axi_clkgen_calc_clk_params(dout, &low, &high, &edge, &nocount);
+ axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_CLK_OUT1,
+ (high << 6) | low);
+ axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_CLK_OUT2,
+ (edge << 7) | (nocount << 6));
+
+ axi_clkgen_calc_clk_params(d, &low, &high, &edge, &nocount);
+ axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_CLK_DIV,
+ (edge << 13) | (nocount << 12) | (high << 6) | low);
+
+ axi_clkgen_calc_clk_params(m, &low, &high, &edge, &nocount);
+ axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_CLK_FB1,
+ (high << 6) | low);
+ axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_CLK_FB2,
+ (edge << 7) | (nocount << 6));
+
+ axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_LOCK1, lock & 0x3ff);
+ axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_LOCK2,
+ (((lock >> 16) & 0x1f) << 10) | 0x1);
+ axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_LOCK3,
+ (((lock >> 24) & 0x1f) << 10) | 0x3e9);
+ axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_FILTER1, filter >> 16);
+ axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_FILTER2, filter);
+
+ axi_clkgen_write(axi_clkgen, AXI_CLKGEN_REG_UPDATE_ENABLE, 1);
+
+ return 0;
+}
+
+static long axi_clkgen_round_rate(struct clk_hw *hw, unsigned long rate,
+ unsigned long *parent_rate)
+{
+ unsigned int d, m, dout;
+
+ axi_clkgen_calc_params(*parent_rate, rate, &d, &m, &dout);
+
+ if (d == 0 || dout == 0 || m == 0)
+ return -EINVAL;
+
+ return *parent_rate / d * m / dout;
+}
+
+static unsigned long axi_clkgen_recalc_rate(struct clk_hw *clk_hw,
+ unsigned long parent_rate)
+{
+ struct axi_clkgen *axi_clkgen = clk_hw_to_axi_clkgen(clk_hw);
+ unsigned int d, m, dout;
+ unsigned int reg;
+ unsigned long long tmp;
+
+ axi_clkgen_read(axi_clkgen, AXI_CLKGEN_REG_CLK_OUT1, &reg);
+ dout = (reg & 0x3f) + ((reg >> 6) & 0x3f);
+ axi_clkgen_read(axi_clkgen, AXI_CLKGEN_REG_CLK_DIV, &reg);
+ d = (reg & 0x3f) + ((reg >> 6) & 0x3f);
+ axi_clkgen_read(axi_clkgen, AXI_CLKGEN_REG_CLK_FB1, &reg);
+ m = (reg & 0x3f) + ((reg >> 6) & 0x3f);
+
+ if (d == 0 || dout == 0)
+ return 0;
+
+ tmp = (unsigned long long)(parent_rate / d) * m;
+ do_div(tmp, dout);
+
+ if (tmp > ULONG_MAX)
+ return ULONG_MAX;
+
+ return tmp;
+}
+
+static const struct clk_ops axi_clkgen_ops = {
+ .recalc_rate = axi_clkgen_recalc_rate,
+ .round_rate = axi_clkgen_round_rate,
+ .set_rate = axi_clkgen_set_rate,
+};
+
+static int axi_clkgen_probe(struct platform_device *pdev)
+{
+ struct axi_clkgen *axi_clkgen;
+ struct clk_init_data init;
+ const char *parent_name;
+ const char *clk_name;
+ struct resource *mem;
+ struct clk *clk;
+
+ axi_clkgen = devm_kzalloc(&pdev->dev, sizeof(*axi_clkgen),
+ GFP_KERNEL);
+ if (!axi_clkgen)
+ return -ENOMEM;
+
+ mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ axi_clkgen->base = devm_request_and_ioremap(&pdev->dev, mem);
+ if (!axi_clkgen->base)
+ return -ENXIO;
+
+ parent_name = of_clk_get_parent_name(pdev->dev.of_node, 0);
+ clk_name = pdev->dev.of_node->name;
+
+ of_property_read_string(pdev->dev.of_node, "clock-output-names",
+ &clk_name);
+
+ init.name = clk_name;
+ init.ops = &axi_clkgen_ops;
+ init.flags = 0;
+ init.parent_names = &parent_name;
+ init.num_parents = 1;
+
+ axi_clkgen->clk_hw.init = &init;
+ clk = devm_clk_register(&pdev->dev, &axi_clkgen->clk_hw);
+ if (IS_ERR(clk))
+ return PTR_ERR(clk);
+
+ of_clk_add_provider(pdev->dev.of_node, of_clk_src_simple_get, clk);
+
+ return 0;
+}
+
+static int axi_clkgen_remove(struct platform_device *pdev)
+{
+ of_clk_del_provider(pdev->dev.of_node);
+
+ return 0;
+}
+
+static const struct of_device_id axi_clkgen_ids[] = {
+ { .compatible = "adi,axi-clkgen-1.00.a" },
+ { },
+};
+MODULE_DEVICE_TABLE(of, axi_clkgen_ids);
+
+static struct platform_driver axi_clkgen_driver = {
+ .driver = {
+ .name = "adi-axi-clkgen",
+ .owner = THIS_MODULE,
+ .of_match_table = axi_clkgen_ids,
+ },
+ .probe = axi_clkgen_probe,
+ .remove = axi_clkgen_remove,
+};
+module_platform_driver(axi_clkgen_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_AUTHOR("Lars-Peter Clausen <lars@xxxxxxxxxx>");
+MODULE_DESCRIPTION("Driver for the Analog Devices AXI clkgen pcore clock generator");
--
1.8.0

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