Message-ID: <1435574652-12133-1-git-send-email-nicolas.ferre@atmel.com>
Date:	Mon, 29 Jun 2015 12:44:12 +0200
From:	Nicolas Ferre <nicolas.ferre@...el.com>
To:	Boris BREZILLON <boris.brezillon@...e-electrons.com>,
	<linux-arm-kernel@...ts.infradead.org>
CC:	<linux-kernel@...r.kernel.org>,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
	Ludovic Desroches <ludovic.desroches@...el.com>,
	Josh Wu <josh.wu@...el.com>, <mturquette@...libre.com>,
	<pebolle@...cali.nl>, Nicolas Ferre <nicolas.ferre@...el.com>
Subject: [PATCH v2] clk: at91: add generated clock driver

Add a new type of clocks that can be provided to a peripheral.
In addition to the peripheral clock, this new clock that can use several
input clocks as parents can generate divided rates.
This would allow a peripheral to have finer grained clocks for generating
a baud rate, clocking an asynchronous part or having more
options in frequency.

Signed-off-by: Nicolas Ferre <nicolas.ferre@...el.com>
---

Changes in v2:
- adapt to new xxx_determine_rate() callback prototype
- fix checkpatch errors and use __func__
- fix handling of clocks without clk-output-range property specified.
  Test if range.max is present before using it
- test clock id only at probe time instead of at each API call
- remove useless tests in clk_generated_set_rate()
- change the meaningless config HAVE_AT91_GENERATED to HAVE_AT91_GENERATED_CLK
- wrap some lines over 80 characters

Paul,

FYI, this patch is adding another type of clock for the upcoming sama5d2 Atmel
SoC.  It adds a new Kconfig option which is not activated yet.
As you can see in the sama5d2 patch series, it is activated there so that we
don't have to track unneeded dependencies.

Thanks, bye,
   Nicolas.


 .../devicetree/bindings/clock/at91-clock.txt       |  35 +++
 arch/arm/mach-at91/Kconfig                         |   3 +
 drivers/clk/at91/Makefile                          |   1 +
 drivers/clk/at91/clk-generated.c                   | 311 +++++++++++++++++++++
 drivers/clk/at91/pmc.c                             |   6 +
 drivers/clk/at91/pmc.h                             |   5 +
 include/linux/clk/at91_pmc.h                       |   7 +
 7 files changed, 368 insertions(+)
 create mode 100644 drivers/clk/at91/clk-generated.c

diff --git a/Documentation/devicetree/bindings/clock/at91-clock.txt b/Documentation/devicetree/bindings/clock/at91-clock.txt
index 5ba6450693b9..5e737d2cd05d 100644
--- a/Documentation/devicetree/bindings/clock/at91-clock.txt
+++ b/Documentation/devicetree/bindings/clock/at91-clock.txt
@@ -77,6 +77,9 @@ Required properties:
 	"atmel,sama5d4-clk-h32mx":
 		at91 h32mx clock
 
+	"atmel,sama5d2-clk-generated":
+		at91 generated clock
+
 Required properties for SCKC node:
 - reg : defines the IO memory reserved for the SCKC.
 - #size-cells : shall be 0 (reg is used to encode clk id).
@@ -461,3 +464,35 @@ For example:
 		compatible = "atmel,sama5d4-clk-h32mx";
 		clocks = <&mck>;
 	};
+
+Required properties for generated clocks:
+- #size-cells : shall be 0 (reg is used to encode clk id).
+- #address-cells : shall be 1 (reg is used to encode clk id).
+- clocks : shall be the generated clock source phandles.
+	e.g. clocks = <&clk32k>, <&main>, <&plladiv>, <&utmi>, <&mck>;
+- name: device tree node describing a specific generated clock.
+	* #clock-cells : from common clock binding; shall be set to 0.
+	* reg: peripheral id. See Atmel's datasheets to get a full
+	  list of peripheral ids.
+	* atmel,clk-output-range : minimum and maximum clock frequency
+	  (two u32 fields).
+
+For example:
+	gck {
+		compatible = "atmel,sama5d2-clk-generated";
+		#address-cells = <1>;
+		#size-cells = <0>;
+		clocks = <&clk32k>, <&main>, <&plladiv>, <&utmi>, <&mck>;
+
+		tcb0_gclk: tcb0_gclk {
+			#clock-cells = <0>;
+			reg = <35>;
+			atmel,clk-output-range = <0 83000000>;
+		};
+
+		pwm_gclk: pwm_gclk {
+			#clock-cells = <0>;
+			reg = <38>;
+			atmel,clk-output-range = <0 83000000>;
+		};
+	};
diff --git a/arch/arm/mach-at91/Kconfig b/arch/arm/mach-at91/Kconfig
index fd95f34945f4..e8273e79f6ba 100644
--- a/arch/arm/mach-at91/Kconfig
+++ b/arch/arm/mach-at91/Kconfig
@@ -90,6 +90,9 @@ config HAVE_AT91_SMD
 config HAVE_AT91_H32MX
 	bool
 
+config HAVE_AT91_GENERATED_CLK
+	bool
+
 config SOC_SAM_V4_V5
 	bool
 
diff --git a/drivers/clk/at91/Makefile b/drivers/clk/at91/Makefile
index 89a48a7bd5df..13e67bd35cff 100644
--- a/drivers/clk/at91/Makefile
+++ b/drivers/clk/at91/Makefile
@@ -10,3 +10,4 @@ obj-$(CONFIG_HAVE_AT91_UTMI)		+= clk-utmi.o
 obj-$(CONFIG_HAVE_AT91_USB_CLK)		+= clk-usb.o
 obj-$(CONFIG_HAVE_AT91_SMD)		+= clk-smd.o
 obj-$(CONFIG_HAVE_AT91_H32MX)		+= clk-h32mx.o
+obj-$(CONFIG_HAVE_AT91_GENERATED_CLK)	+= clk-generated.o
diff --git a/drivers/clk/at91/clk-generated.c b/drivers/clk/at91/clk-generated.c
new file mode 100644
index 000000000000..1d0c920604b7
--- /dev/null
+++ b/drivers/clk/at91/clk-generated.c
@@ -0,0 +1,311 @@
+/*
+ *  Copyright (C) 2015 Atmel Corporation,
+ *                     Nicolas Ferre <nicolas.ferre@...el.com>
+ *
+ * Based on clk-programmable & clk-peripheral drivers by Boris BREZILLON.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ */
+
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>
+#include <linux/clk/at91_pmc.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/io.h>
+
+#include "pmc.h"
+
+#define PERIPHERAL_MAX		64
+#define PERIPHERAL_ID_MIN	2
+
+#define GENERATED_SOURCE_MAX	6
+#define GENERATED_MAX_DIV	255
+
+struct clk_generated {
+	struct clk_hw hw;
+	struct at91_pmc *pmc;
+	struct clk_range range;
+	u32 id;
+	u32 gckdiv;
+	u8 parent_id;
+};
+
+#define to_clk_generated(hw) \
+	container_of(hw, struct clk_generated, hw)
+
+static int clk_generated_enable(struct clk_hw *hw)
+{
+	struct clk_generated *gck = to_clk_generated(hw);
+	struct at91_pmc *pmc = gck->pmc;
+	u32 tmp;
+
+	pr_debug("GCLK: %s, gckdiv = %d, parent id = %d\n",
+		 __func__, gck->gckdiv, gck->parent_id);
+
+	pmc_lock(pmc);
+	pmc_write(pmc, AT91_PMC_PCR, (gck->id & AT91_PMC_PCR_PID_MASK));
+	tmp = pmc_read(pmc, AT91_PMC_PCR) &
+			~(AT91_PMC_PCR_GCKDIV_MASK | AT91_PMC_PCR_GCKCSS_MASK);
+	pmc_write(pmc, AT91_PMC_PCR, tmp | AT91_PMC_PCR_GCKCSS(gck->parent_id)
+					 | AT91_PMC_PCR_CMD
+					 | AT91_PMC_PCR_GCKDIV(gck->gckdiv)
+					 | AT91_PMC_PCR_GCKEN);
+	pmc_unlock(pmc);
+	return 0;
+}
+
+static void clk_generated_disable(struct clk_hw *hw)
+{
+	struct clk_generated *gck = to_clk_generated(hw);
+	struct at91_pmc *pmc = gck->pmc;
+	u32 tmp;
+
+	pmc_lock(pmc);
+	pmc_write(pmc, AT91_PMC_PCR, (gck->id & AT91_PMC_PCR_PID_MASK));
+	tmp = pmc_read(pmc, AT91_PMC_PCR) & ~AT91_PMC_PCR_GCKEN;
+	pmc_write(pmc, AT91_PMC_PCR, tmp | AT91_PMC_PCR_CMD);
+	pmc_unlock(pmc);
+}
+
+static int clk_generated_is_enabled(struct clk_hw *hw)
+{
+	struct clk_generated *gck = to_clk_generated(hw);
+	struct at91_pmc *pmc = gck->pmc;
+	int ret;
+
+	pmc_lock(pmc);
+	pmc_write(pmc, AT91_PMC_PCR, (gck->id & AT91_PMC_PCR_PID_MASK));
+	ret = !!(pmc_read(pmc, AT91_PMC_PCR) & AT91_PMC_PCR_GCKEN);
+	pmc_unlock(pmc);
+
+	return ret;
+}
+
+static unsigned long
+clk_generated_recalc_rate(struct clk_hw *hw,
+			  unsigned long parent_rate)
+{
+	struct clk_generated *gck = to_clk_generated(hw);
+
+	return DIV_ROUND_CLOSEST(parent_rate, gck->gckdiv + 1);
+}
+
+static long clk_generated_determine_rate(struct clk_hw *hw,
+					 unsigned long rate,
+					 unsigned long min_rate,
+					 unsigned long max_rate,
+					 unsigned long *best_parent_rate,
+					 struct clk_hw **best_parent_hw)
+{
+	struct clk_generated *gck = to_clk_generated(hw);
+	struct clk *parent = NULL;
+	long best_rate = -EINVAL;
+	unsigned long tmp_rate, min_rate;
+	int best_diff = -1;
+	int tmp_diff;
+	int i;
+
+	for (i = 0; i < __clk_get_num_parents(hw->clk); i++) {
+		u32 div;
+		unsigned long parent_rate;
+
+		parent = clk_get_parent_by_index(hw->clk, i);
+		if (!parent)
+			continue;
+
+		parent_rate = __clk_get_rate(parent);
+		min_rate = DIV_ROUND_CLOSEST(parent_rate, GENERATED_MAX_DIV + 1);
+		if (!parent_rate ||
+		    (gck->range.max && min_rate > gck->range.max))
+			continue;
+
+		for (div = 1; div < GENERATED_MAX_DIV + 2; div++) {
+
+			tmp_rate = DIV_ROUND_CLOSEST(parent_rate, div);
+			tmp_diff = abs(rate - tmp_rate);
+
+			if (best_diff < 0 || best_diff > tmp_diff) {
+				best_rate = tmp_rate;
+				best_diff = tmp_diff;
+				*best_parent_rate = parent_rate;
+				*best_parent_hw = __clk_get_hw(parent);
+			}
+
+			if (!best_diff || tmp_rate < rate)
+				break;
+		}
+
+		if (!best_diff)
+			break;
+	}
+
+	pr_debug("GCLK: %s, best_rate = %ld, parent clk: %s @ %ld\n",
+		 __func__, best_rate,
+		 __clk_get_name((*best_parent_hw)->clk), *best_parent_rate);
+
+	return best_rate;
+}
+
+/* No modification of hardware as we have the flag CLK_SET_PARENT_GATE set */
+static int clk_generated_set_parent(struct clk_hw *hw, u8 index)
+{
+	struct clk_generated *gck = to_clk_generated(hw);
+
+	if (index >= __clk_get_num_parents(hw->clk))
+		return -EINVAL;
+
+	gck->parent_id = index;
+	return 0;
+}
+
+static u8 clk_generated_get_parent(struct clk_hw *hw)
+{
+	struct clk_generated *gck = to_clk_generated(hw);
+
+	return gck->parent_id;
+}
+
+/* No modification of hardware as we have the flag CLK_SET_RATE_GATE set */
+static int clk_generated_set_rate(struct clk_hw *hw,
+				    unsigned long rate,
+				    unsigned long parent_rate)
+{
+	struct clk_generated *gck = to_clk_generated(hw);
+	u32 div;
+
+	if (!rate)
+		return -EINVAL;
+
+	if (gck->range.max && rate > gck->range.max)
+		return -EINVAL;
+
+	div = DIV_ROUND_CLOSEST(parent_rate, rate);
+	if (div > GENERATED_MAX_DIV + 1 || !div)
+		return -EINVAL;
+
+	gck->gckdiv = div - 1;
+	return 0;
+}
+
+static const struct clk_ops generated_ops = {
+	.enable = clk_generated_enable,
+	.disable = clk_generated_disable,
+	.is_enabled = clk_generated_is_enabled,
+	.recalc_rate = clk_generated_recalc_rate,
+	.determine_rate = clk_generated_determine_rate,
+	.get_parent = clk_generated_get_parent,
+	.set_parent = clk_generated_set_parent,
+	.set_rate = clk_generated_set_rate,
+};
+
+/**
+ * clk_generated_startup - Initialize a given clock to its default parent and
+ * divisor parameter.
+ *
+ * @gck:	Generated clock to set the startup parameters for.
+ *
+ * Take parameters from the hardware and update local clock configuration
+ * accordingly.
+ */
+static void clk_generated_startup(struct clk_generated *gck)
+{
+	struct at91_pmc *pmc = gck->pmc;
+	u32 tmp;
+
+	pmc_lock(pmc);
+	pmc_write(pmc, AT91_PMC_PCR, (gck->id & AT91_PMC_PCR_PID_MASK));
+	tmp = pmc_read(pmc, AT91_PMC_PCR);
+	pmc_unlock(pmc);
+
+	gck->parent_id = (tmp & AT91_PMC_PCR_GCKCSS_MASK)
+					>> AT91_PMC_PCR_GCKCSS_OFFSET;
+	gck->gckdiv = (tmp & AT91_PMC_PCR_GCKDIV_MASK)
+					>> AT91_PMC_PCR_GCKDIV_OFFSET;
+}
+
+static struct clk * __init
+at91_clk_register_generated(struct at91_pmc *pmc, const char *name,
+			    const char **parent_names, u8 num_parents,
+			    u8 id, const struct clk_range *range)
+{
+	struct clk_generated *gck;
+	struct clk *clk = NULL;
+	struct clk_init_data init;
+
+	gck = kzalloc(sizeof(*gck), GFP_KERNEL);
+	if (!gck)
+		return ERR_PTR(-ENOMEM);
+
+	init.name = name;
+	init.ops = &generated_ops;
+	init.parent_names = parent_names;
+	init.num_parents = num_parents;
+	init.flags = CLK_SET_RATE_GATE | CLK_SET_PARENT_GATE;
+
+	gck->id = id;
+	gck->hw.init = &init;
+	gck->pmc = pmc;
+	gck->range = *range;
+
+	clk = clk_register(NULL, &gck->hw);
+	if (IS_ERR(clk))
+		kfree(gck);
+	else
+		clk_generated_startup(gck);
+
+	return clk;
+}
+
+void __init of_sama5d2_clk_generated_setup(struct device_node *np,
+					   struct at91_pmc *pmc)
+{
+	int i;
+	int num;
+	u32 id;
+	const char *name;
+	struct clk *clk;
+	int num_parents;
+	const char *parent_names[GENERATED_SOURCE_MAX];
+	struct device_node *gcknp;
+	struct clk_range range = CLK_RANGE(0, 0);
+
+	num_parents = of_count_phandle_with_args(np, "clocks", "#clock-cells");
+	if (num_parents <= 0 || num_parents > GENERATED_SOURCE_MAX)
+		return;
+
+	for (i = 0; i < num_parents; ++i) {
+		parent_names[i] = of_clk_get_parent_name(np, i);
+		if (!parent_names[i])
+			return;
+	}
+
+	num = of_get_child_count(np);
+	if (!num || num > PERIPHERAL_MAX)
+		return;
+
+	for_each_child_of_node(np, gcknp) {
+		if (of_property_read_u32(gcknp, "reg", &id))
+			continue;
+
+		if (id < PERIPHERAL_ID_MIN || id >= PERIPHERAL_MAX)
+			continue;
+
+		if (of_property_read_string(np, "clock-output-names", &name))
+			name = gcknp->name;
+
+		of_at91_get_clk_range(gcknp, "atmel,clk-output-range",
+				      &range);
+
+		clk = at91_clk_register_generated(pmc, name, parent_names,
+						  num_parents, id, &range);
+		if (IS_ERR(clk))
+			continue;
+
+		of_clk_add_provider(gcknp, of_clk_src_simple_get, clk);
+	}
+}
diff --git a/drivers/clk/at91/pmc.c b/drivers/clk/at91/pmc.c
index 39be2be82b0a..3775d82c213d 100644
--- a/drivers/clk/at91/pmc.c
+++ b/drivers/clk/at91/pmc.c
@@ -370,6 +370,12 @@ static const struct of_device_id pmc_clk_ids[] __initconst = {
 		.data = of_sama5d4_clk_h32mx_setup,
 	},
 #endif
+#if defined(CONFIG_HAVE_AT91_GENERATED_CLK)
+	{
+		.compatible = "atmel,sama5d2-clk-generated",
+		.data = of_sama5d2_clk_generated_setup,
+	},
+#endif
 	{ /*sentinel*/ }
 };
 
diff --git a/drivers/clk/at91/pmc.h b/drivers/clk/at91/pmc.h
index 69abb08cf146..0b03cfcef56f 100644
--- a/drivers/clk/at91/pmc.h
+++ b/drivers/clk/at91/pmc.h
@@ -126,4 +126,9 @@ extern void __init of_sama5d4_clk_h32mx_setup(struct device_node *np,
 					      struct at91_pmc *pmc);
 #endif
 
+#if defined(CONFIG_HAVE_AT91_GENERATED_CLK)
+extern void __init of_sama5d2_clk_generated_setup(struct device_node *np,
+						  struct at91_pmc *pmc);
+#endif
+
 #endif /* __PMC_H_ */
diff --git a/include/linux/clk/at91_pmc.h b/include/linux/clk/at91_pmc.h
index dfc59e2b64fb..ae61860e6892 100644
--- a/include/linux/clk/at91_pmc.h
+++ b/include/linux/clk/at91_pmc.h
@@ -183,10 +183,17 @@ extern void __iomem *at91_pmc_base;
 
 #define AT91_PMC_PCR		0x10c			/* Peripheral Control Register [some SAM9 and SAMA5] */
 #define		AT91_PMC_PCR_PID_MASK		0x3f
+#define		AT91_PMC_PCR_GCKCSS_OFFSET	8
+#define		AT91_PMC_PCR_GCKCSS_MASK	(0x7  << AT91_PMC_PCR_GCKCSS_OFFSET)
+#define		AT91_PMC_PCR_GCKCSS(n)		((n)  << AT91_PMC_PCR_GCKCSS_OFFSET)	/* GCK Clock Source Selection */
 #define		AT91_PMC_PCR_CMD		(0x1  <<  12)				/* Command (read=0, write=1) */
 #define		AT91_PMC_PCR_DIV_OFFSET		16
 #define		AT91_PMC_PCR_DIV_MASK		(0x3  << AT91_PMC_PCR_DIV_OFFSET)
 #define		AT91_PMC_PCR_DIV(n)		((n)  << AT91_PMC_PCR_DIV_OFFSET)	/* Divisor Value */
+#define		AT91_PMC_PCR_GCKDIV_OFFSET	20
+#define		AT91_PMC_PCR_GCKDIV_MASK	(0xff  << AT91_PMC_PCR_GCKDIV_OFFSET)
+#define		AT91_PMC_PCR_GCKDIV(n)		((n)  << AT91_PMC_PCR_GCKDIV_OFFSET)	/* Generated Clock Divisor Value */
 #define		AT91_PMC_PCR_EN			(0x1  <<  28)				/* Enable */
+#define		AT91_PMC_PCR_GCKEN		(0x1  <<  29)				/* GCK Enable */
 
 #endif
-- 
2.1.3

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