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>

1 files changed, 123 insertions, 0 deletions

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);
+}