1 files changed, 131 insertions, 0 deletions
diff --git a/drivers/clocksource/clksrc_st_lpc.c b/drivers/clocksource/clksrc_st_lpc.c
new file mode 100644
index 000000000..419a88687
--- /dev/null
+++ b/drivers/clocksource/clksrc_st_lpc.c
@@ -0,0 +1,131 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Clocksource using the Low Power Timer found in the Low Power Controller (LPC)
+ *
+ * Copyright (C) 2015 STMicroelectronics – All Rights Reserved
+ *
+ * Author(s): Francesco Virlinzi <francesco.virlinzi@st.com>
+ *	      Ajit Pal Singh <ajitpal.singh@st.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/clocksource.h>
+#include <linux/init.h>
+#include <linux/of_address.h>
+#include <linux/sched_clock.h>
+#include <linux/slab.h>
+
+#include <dt-bindings/mfd/st-lpc.h>
+
+/* Low Power Timer */
+#define LPC_LPT_LSB_OFF		0x400
+#define LPC_LPT_MSB_OFF		0x404
+#define LPC_LPT_START_OFF	0x408
+
+static struct st_clksrc_ddata {
+	struct clk		*clk;
+	void __iomem		*base;
+} ddata;
+
+static void __init st_clksrc_reset(void)
+{
+	writel_relaxed(0, ddata.base + LPC_LPT_START_OFF);
+	writel_relaxed(0, ddata.base + LPC_LPT_MSB_OFF);
+	writel_relaxed(0, ddata.base + LPC_LPT_LSB_OFF);
+	writel_relaxed(1, ddata.base + LPC_LPT_START_OFF);
+}
+
+static u64 notrace st_clksrc_sched_clock_read(void)
+{
+	return (u64)readl_relaxed(ddata.base + LPC_LPT_LSB_OFF);
+}
+
+static int __init st_clksrc_init(void)
+{
+	unsigned long rate;
+	int ret;
+
+	st_clksrc_reset();
+
+	rate = clk_get_rate(ddata.clk);
+
+	sched_clock_register(st_clksrc_sched_clock_read, 32, rate);
+
+	ret = clocksource_mmio_init(ddata.base + LPC_LPT_LSB_OFF,
+				    "clksrc-st-lpc", rate, 300, 32,
+				    clocksource_mmio_readl_up);
+	if (ret) {
+		pr_err("clksrc-st-lpc: Failed to register clocksource\n");
+		return ret;
+	}
+
+	return 0;
+}
+
+static int __init st_clksrc_setup_clk(struct device_node *np)
+{
+	struct clk *clk;
+
+	clk = of_clk_get(np, 0);
+	if (IS_ERR(clk)) {
+		pr_err("clksrc-st-lpc: Failed to get LPC clock\n");
+		return PTR_ERR(clk);
+	}
+
+	if (clk_prepare_enable(clk)) {
+		pr_err("clksrc-st-lpc: Failed to enable LPC clock\n");
+		return -EINVAL;
+	}
+
+	if (!clk_get_rate(clk)) {
+		pr_err("clksrc-st-lpc: Failed to get LPC clock rate\n");
+		clk_disable_unprepare(clk);
+		return -EINVAL;
+	}
+
+	ddata.clk = clk;
+
+	return 0;
+}
+
+static int __init st_clksrc_of_register(struct device_node *np)
+{
+	int ret;
+	uint32_t mode;
+
+	ret = of_property_read_u32(np, "st,lpc-mode", &mode);
+	if (ret) {
+		pr_err("clksrc-st-lpc: An LPC mode must be provided\n");
+		return ret;
+	}
+
+	/* LPC can either run as a Clocksource or in RTC or WDT mode */
+	if (mode != ST_LPC_MODE_CLKSRC)
+		return 0;
+
+	ddata.base = of_iomap(np, 0);
+	if (!ddata.base) {
+		pr_err("clksrc-st-lpc: Unable to map iomem\n");
+		return -ENXIO;
+	}
+
+	ret = st_clksrc_setup_clk(np);
+	if (ret) {
+		iounmap(ddata.base);
+		return ret;
+	}
+
+	ret = st_clksrc_init();
+	if (ret) {
+		clk_disable_unprepare(ddata.clk);
+		clk_put(ddata.clk);
+		iounmap(ddata.base);
+		return ret;
+	}
+
+	pr_info("clksrc-st-lpc: clocksource initialised - running @ %luHz\n",
+		clk_get_rate(ddata.clk));
+
+	return ret;
+}
+TIMER_OF_DECLARE(ddata, "st,stih407-lpc", st_clksrc_of_register);