clk: at91: add a driver for the h32mx clock

Newer SoCs have two different AHB interconnect. The AHB 32 bits Matrix
interconnect (h32mx) has a clock that can be setup at the half of the h64mx
clock (which is mck). The h32mx clock can not exceed 90 MHz.

Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>

7 files changed, 153 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/clock/at91-clock.txt b/Documentation/devicetree/bindings/clock/at91-clock.txt
index b3d544ca522a..7a4d4926f44e 100644
--- a/Documentation/devicetree/bindings/clock/at91-clock.txt
+++ b/Documentation/devicetree/bindings/clock/at91-clock.txt
@@ -74,6 +74,9 @@ Required properties:
         "atmel,at91sam9x5-clk-utmi":
                 at91 utmi clock
 
+        "atmel,sama5d4-clk-h32mx":
+                at91 h32mx 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).
@@ -447,3 +450,14 @@ For example:
                 #clock-cells = <0>;
                 clocks = <&main>;
         };
+
+Required properties for 32 bits bus Matrix clock (h32mx clock):
+- #clock-cells : from common clock binding; shall be set to 0.
+- clocks : shall be the master clock source phandle.
+
+For example:
+        h32ck: h32mxck {
+                #clock-cells = <0>;
+                compatible = "atmel,sama5d4-clk-h32mx";
+                clocks = <&mck>;
+        };
diff --git a/arch/arm/mach-at91/Kconfig b/arch/arm/mach-at91/Kconfig
index 6cc6f7aebdae..321210cc3be7 100644
--- a/arch/arm/mach-at91/Kconfig
+++ b/arch/arm/mach-at91/Kconfig
@@ -42,6 +42,9 @@ config AT91_SAM9_TIME
 config HAVE_AT91_SMD
         bool
 
+config HAVE_AT91_H32MX
+        bool
+
 config SOC_AT91SAM9
         bool
         select AT91_SAM9_TIME
diff --git a/drivers/clk/at91/Makefile b/drivers/clk/at91/Makefile
index 4998aee59267..89a48a7bd5df 100644
--- a/drivers/clk/at91/Makefile
+++ b/drivers/clk/at91/Makefile
@@ -9,3 +9,4 @@ obj-y += clk-system.o clk-peripheral.o clk-programmable.o
 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
diff --git a/drivers/clk/at91/clk-h32mx.c b/drivers/clk/at91/clk-h32mx.c
new file mode 100644
index 000000000000..152dcb3f7b5f
--- /dev/null
+++ b/drivers/clk/at91/clk-h32mx.c
@@ -0,0 +1,123 @@
+/*
+ * clk-h32mx.c
+ *
+ *  Copyright (C) 2014 Atmel
+ *
+ * Alexandre Belloni <alexandre.belloni@free-electrons.com>
+ *
+ * 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/delay.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/sched.h>
+#include <linux/wait.h>
+
+#include "pmc.h"
+
+#define H32MX_MAX_FREQ  90000000
+
+struct clk_sama5d4_h32mx {
+        struct clk_hw hw;
+        struct at91_pmc *pmc;
+};
+
+#define to_clk_sama5d4_h32mx(hw) container_of(hw, struct clk_sama5d4_h32mx, hw)
+
+static unsigned long clk_sama5d4_h32mx_recalc_rate(struct clk_hw *hw,
+                                                 unsigned long parent_rate)
+{
+        struct clk_sama5d4_h32mx *h32mxclk = to_clk_sama5d4_h32mx(hw);
+
+        if (pmc_read(h32mxclk->pmc, AT91_PMC_MCKR) & AT91_PMC_H32MXDIV)
+                return parent_rate / 2;
+
+        if (parent_rate > H32MX_MAX_FREQ)
+                pr_warn("H32MX clock is too fast\n");
+        return parent_rate;
+}
+
+static long clk_sama5d4_h32mx_round_rate(struct clk_hw *hw, unsigned long rate,
+                                       unsigned long *parent_rate)
+{
+        unsigned long div;
+
+        if (rate > *parent_rate)
+                return *parent_rate;
+        div = *parent_rate / 2;
+        if (rate < div)
+                return div;
+
+        if (rate - div < *parent_rate - rate)
+                return div;
+
+        return *parent_rate;
+}
+
+static int clk_sama5d4_h32mx_set_rate(struct clk_hw *hw, unsigned long rate,
+                                    unsigned long parent_rate)
+{
+        struct clk_sama5d4_h32mx *h32mxclk = to_clk_sama5d4_h32mx(hw);
+        struct at91_pmc *pmc = h32mxclk->pmc;
+        u32 tmp;
+
+        if (parent_rate != rate && (parent_rate / 2) != rate)
+                return -EINVAL;
+
+        pmc_lock(pmc);
+        tmp = pmc_read(pmc, AT91_PMC_MCKR) & ~AT91_PMC_H32MXDIV;
+        if ((parent_rate / 2) == rate)
+                tmp |= AT91_PMC_H32MXDIV;
+        pmc_write(pmc, AT91_PMC_MCKR, tmp);
+        pmc_unlock(pmc);
+
+        return 0;
+}
+
+static const struct clk_ops h32mx_ops = {
+        .recalc_rate = clk_sama5d4_h32mx_recalc_rate,
+        .round_rate = clk_sama5d4_h32mx_round_rate,
+        .set_rate = clk_sama5d4_h32mx_set_rate,
+};
+
+void __init of_sama5d4_clk_h32mx_setup(struct device_node *np,
+                                     struct at91_pmc *pmc)
+{
+        struct clk_sama5d4_h32mx *h32mxclk;
+        struct clk_init_data init;
+        const char *parent_name;
+        struct clk *clk;
+
+        h32mxclk = kzalloc(sizeof(*h32mxclk), GFP_KERNEL);
+        if (!h32mxclk)
+                return;
+
+        parent_name = of_clk_get_parent_name(np, 0);
+
+        init.name = np->name;
+        init.ops = &h32mx_ops;
+        init.parent_names = parent_name ? &parent_name : NULL;
+        init.num_parents = parent_name ? 1 : 0;
+        init.flags = CLK_SET_RATE_GATE;
+
+        h32mxclk->hw.init = &init;
+        h32mxclk->pmc = pmc;
+
+        clk = clk_register(NULL, &h32mxclk->hw);
+        if (!clk)
+                return;
+
+        of_clk_add_provider(np, of_clk_src_simple_get, clk);
+}
diff --git a/drivers/clk/at91/pmc.c b/drivers/clk/at91/pmc.c
index 524196bb35a5..386999b4f8eb 100644
--- a/drivers/clk/at91/pmc.c
+++ b/drivers/clk/at91/pmc.c
@@ -337,6 +337,12 @@ static const struct of_device_id pmc_clk_ids[] __initconst = {
                 .data = of_at91sam9x5_clk_smd_setup,
         },
 #endif
+#if defined(CONFIG_HAVE_AT91_H32MX)
+        {
+                .compatible = "atmel,sama5d4-clk-h32mx",
+                .data = of_sama5d4_clk_h32mx_setup,
+        },
+#endif
         { /*sentinel*/ }
 };
 
diff --git a/drivers/clk/at91/pmc.h b/drivers/clk/at91/pmc.h
index 6c7625976113..52d2041fa3f6 100644
--- a/drivers/clk/at91/pmc.h
+++ b/drivers/clk/at91/pmc.h
@@ -120,4 +120,9 @@ extern void __init of_at91sam9x5_clk_smd_setup(struct device_node *np,
                                                struct at91_pmc *pmc);
 #endif
 
+#if defined(CONFIG_HAVE_AT91_SMD)
+extern void __init of_sama5d4_clk_h32mx_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 de4268d4987a..c8e3b3d1eded 100644
--- a/include/linux/clk/at91_pmc.h
+++ b/include/linux/clk/at91_pmc.h
@@ -125,6 +125,7 @@ extern void __iomem *at91_pmc_base;
 #define         AT91_PMC_PLLADIV2       (1 << 12)               /* PLLA divisor by 2 [some SAM9 only] */
 #define                 AT91_PMC_PLLADIV2_OFF           (0 << 12)
 #define                 AT91_PMC_PLLADIV2_ON            (1 << 12)
+#define         AT91_PMC_H32MXDIV       BIT(24)
 
 #define AT91_PMC_USB            0x38                    /* USB Clock Register [some SAM9 only] */
 #define         AT91_PMC_USBS           (0x1 <<  0)             /* USB OHCI Input clock selection */