[PATCH 04/13] clk: tegra: Add functions for parsing CVB tables

Tuomas Tynkkynen
2014-07-10T21:43:35Z

Tegra CVB tables encode the relationship between operating voltage and
optimal frequency as a second-order polynomial of the so-called speedo
value. The speedo value is written to the on-chip fuses at the factory,
which allows the voltage-frequency operating points to be calculated on
an per-chip basis.

Add utility functions to parse the Tegra-specific tables and export the
voltage-frequency pairs to the generic OPP framework for other drivers
to use.

Signed-off-by: Tuomas Tynkkynen <ttynkkynen@nvidia.com>
---
arch/arm/mach-tegra/Kconfig | 1 +
drivers/clk/tegra/cvb.c | 133 ++++++++++++++++++++++++++++++++++++++++++++
drivers/clk/tegra/cvb.h | 67 ++++++++++++++++++++++
3 files changed, 201 insertions(+)
create mode 100644 drivers/clk/tegra/cvb.c
create mode 100644 drivers/clk/tegra/cvb.h

diff --git a/arch/arm/mach-tegra/Kconfig b/arch/arm/mach-tegra/Kconfig
index 0953996..0d5832f 100644
--- a/arch/arm/mach-tegra/Kconfig
+++ b/arch/arm/mach-tegra/Kconfig
@@ -7,6 +7,7 @@ menuconfig ARCH_TEGRA
select HAVE_ARM_SCU if SMP
select HAVE_ARM_TWD if SMP
select PINCTRL
+ select PM_OPP
select ARCH_HAS_RESET_CONTROLLER
select RESET_CONTROLLER
select SOC_BUS
diff --git a/drivers/clk/tegra/cvb.c b/drivers/clk/tegra/cvb.c
new file mode 100644
index 0000000..69c74ee
--- /dev/null
+++ b/drivers/clk/tegra/cvb.c
@@ -0,0 +1,133 @@
+/*
+ * Utility functions for parsing Tegra CVB voltage tables
+ *
+ * Copyright (C) 2012-2014 NVIDIA Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ */
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/pm_opp.h>
+
+#include "cvb.h"
+
+/* cvb_mv = ((c2 * speedo / s_scale + c1) * speedo / s_scale + c0) */
+static inline int get_cvb_voltage(int speedo, int s_scale,
+ const struct cvb_coefficients *cvb)
+{
+ int mv;
+
+ /* apply only speedo scale: output mv = cvb_mv * v_scale */
+ mv = DIV_ROUND_CLOSEST(cvb->c2 * speedo, s_scale);
+ mv = DIV_ROUND_CLOSEST((mv + cvb->c1) * speedo, s_scale) + cvb->c0;
+ return mv;
+}
+
+static int round_cvb_voltage(int mv, int v_scale,
+ const struct rail_alignment *align)
+{
+ /* combined: apply voltage scale and round to cvb alignment step */
+ int uv;
+ int step = (align->step_uv ? : 1000) * v_scale;
+ int offset = align->offset_uv * v_scale;
+
+ uv = max(mv * 1000, offset) - offset;
+ uv = DIV_ROUND_UP(uv, step) * align->step_uv + align->offset_uv;
+ return uv / 1000;
+}
+
+enum {
+ DOWN,
+ UP
+};
+
+static int round_voltage(int mv, const struct rail_alignment *align, int up)
+{
+ if (align->step_uv) {
+ int uv;
+
+ uv = max(mv * 1000, align->offset_uv) - align->offset_uv;
+ uv = (uv + (up ? align->step_uv - 1 : 0)) / align->step_uv;
+ return (uv * align->step_uv + align->offset_uv) / 1000;
+ }
+ return mv;
+}
+
+static int build_opp_table(const struct cvb_table *d,
+ int speedo_value,
+ unsigned long max_freq,
+ struct device *opp_dev)
+{
+ int i, ret, dfll_mv, min_mv, max_mv;
+ const struct cvb_table_freq_entry *table = NULL;
+ const struct rail_alignment *align = &d->alignment;
+
+ min_mv = round_voltage(d->min_millivolts, align, UP);
+ max_mv = round_voltage(d->max_millivolts, align, DOWN);
+
+ for (i = 0; i < MAX_DVFS_FREQS; i++) {
+ table = &d->cvb_table[i];
+ if (!table->freq || (table->freq > max_freq))
+ break;
+
+ dfll_mv = get_cvb_voltage(
+ speedo_value, d->speedo_scale, &table->coefficients);
+ dfll_mv = round_cvb_voltage(dfll_mv, d->voltage_scale, align);
+ dfll_mv = clamp(dfll_mv, min_mv, max_mv);
+
+ ret = dev_pm_opp_add(opp_dev, table->freq, dfll_mv * 1000);
+ if (ret)
+ return ret;
+ }
+
+ return 0;
+}
+
+/**
+ * tegra_cvb_build_opp_table - build OPP table from Tegra CVB tables
+ * @cvb_tables: array of CVB tables
+ * @sz: size of the previously mentioned array
+ * @process_id: process id of the HW module
+ * @speedo_id: speedo id of the HW module
+ * @speedo_value: speedo value of the HW module
+ * @max_rate: highest safe clock rate
+ * @opp_dev: the struct device * for which the OPP table is built
+ *
+ * On Tegra, a CVB table encodes the relationship between operating voltage
+ * and safe maximal frequency for a given module (e.g. GPU or CPU). This
+ * function calculates the optimal voltage-frequency operating points
+ * for the given arguments and exports them via the OPP library for the
+ * given @opp_dev. Returns a pointer to the struct cvb_table that matched
+ * or an ERR_PTR on failure.
+ */
+const struct cvb_table *tegra_cvb_build_opp_table(
+ const struct cvb_table *cvb_tables,
+ size_t sz, int process_id,
+ int speedo_id, int speedo_value,
+ unsigned long max_rate,
+ struct device *opp_dev)
+{
+ int i, ret;
+
+ for (i = 0; i < sz; i++) {
+ const struct cvb_table *d = &cvb_tables[i];
+
+ if (d->speedo_id != -1 && d->speedo_id != speedo_id)
+ continue;
+ if (d->process_id != -1 && d->process_id != process_id)
+ continue;
+
+ ret = build_opp_table(d, speedo_value, max_rate, opp_dev);
+ return ret ? ERR_PTR(ret) : d;
+ }
+
+ return ERR_PTR(-EINVAL);
+}
diff --git a/drivers/clk/tegra/cvb.h b/drivers/clk/tegra/cvb.h
new file mode 100644
index 0000000..f62cdc4
--- /dev/null
+++ b/drivers/clk/tegra/cvb.h
@@ -0,0 +1,67 @@
+/*
+ * Utility functions for parsing Tegra CVB voltage tables
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+ * more details.
+ *
+ */
+
+#ifndef __DRIVERS_CLK_TEGRA_CVB_H
+#define __DRIVERS_CLK_TEGRA_CVB_H
+
+#include <linux/types.h>
+
+struct device;
+
+#define MAX_DVFS_FREQS 40
+
+struct rail_alignment {
+ int offset_uv;
+ int step_uv;
+};
+
+struct cvb_coefficients {
+ int c0;
+ int c1;
+ int c2;
+};
+
+struct cvb_table_freq_entry {
+ unsigned long freq;
+ struct cvb_coefficients coefficients;
+};
+
+struct cvb_cpu_dfll_data {
+ u32 tune0_low;
+ u32 tune0_high;
+ u32 tune1;
+};
+
+struct cvb_table {
+ int speedo_id;
+ int process_id;
+
+ int min_millivolts;
+ int max_millivolts;
+ struct rail_alignment alignment;
+
+ int speedo_scale;
+ int voltage_scale;
+ struct cvb_table_freq_entry cvb_table[MAX_DVFS_FREQS];
+ struct cvb_cpu_dfll_data cpu_dfll_data;
+};
+
+const struct cvb_table *tegra_cvb_build_opp_table(
+ const struct cvb_table *cvb_tables,
+ size_t sz, int process_id,
+ int speedo_id, int speedo_value,
+ unsigned long max_rate,
+ struct device *opp_dev);
+
+#endif
--
1.8.1.5