thermal: rcar_gen3_thermal: Add R-Car Gen3 thermal driver

Add support for R-Car Gen3 thermal sensors. Polling only for now,
interrupts will be added incrementally. Same goes for reading fuses.
This is documented already, but no hardware available for now.

Signed-off-by: Hien Dang <hien.dang.eb@renesas.com>
Signed-off-by: Thao Nguyen <thao.nguyen.yb@rvc.renesas.com>
Signed-off-by: Khiem Nguyen <khiem.nguyen.xt@renesas.com>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
[Niklas: document and rework temperature calculation]
Signed-off-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Eduardo Valentin <edubezval@gmail.com>

3 files changed, 345 insertions, 0 deletions

diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
index c2c056cc7ea5..3912d24a07b1 100644
--- a/drivers/thermal/Kconfig
+++ b/drivers/thermal/Kconfig
@@ -245,6 +245,15 @@ config RCAR_THERMAL
           Enable this to plug the R-Car thermal sensor driver into the Linux
           thermal framework.
 
+config RCAR_GEN3_THERMAL
+        tristate "Renesas R-Car Gen3 thermal driver"
+        depends on ARCH_RENESAS || COMPILE_TEST
+        depends on HAS_IOMEM
+        depends on OF
+        help
+          Enable this to plug the R-Car Gen3 thermal sensor driver into the Linux
+          thermal framework.
+
 config KIRKWOOD_THERMAL
         tristate "Temperature sensor on Marvell Kirkwood SoCs"
         depends on MACH_KIRKWOOD || COMPILE_TEST
diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
index 6a3d7b573036..adcf3cc90859 100644
--- a/drivers/thermal/Makefile
+++ b/drivers/thermal/Makefile
@@ -31,6 +31,7 @@ obj-$(CONFIG_QCOM_SPMI_TEMP_ALARM)	+= qcom-spmi-temp-alarm.o
 obj-$(CONFIG_SPEAR_THERMAL)     += spear_thermal.o
 obj-$(CONFIG_ROCKCHIP_THERMAL)  += rockchip_thermal.o
 obj-$(CONFIG_RCAR_THERMAL)      += rcar_thermal.o
+obj-$(CONFIG_RCAR_GEN3_THERMAL) += rcar_gen3_thermal.o
 obj-$(CONFIG_KIRKWOOD_THERMAL)  += kirkwood_thermal.o
 obj-y                           += samsung/
 obj-$(CONFIG_DOVE_THERMAL)      += dove_thermal.o
diff --git a/drivers/thermal/rcar_gen3_thermal.c b/drivers/thermal/rcar_gen3_thermal.c
new file mode 100644
index 000000000000..d33c845244b1
--- /dev/null
+++ b/drivers/thermal/rcar_gen3_thermal.c
@@ -0,0 +1,335 @@
+/*
+ *  R-Car Gen3 THS thermal sensor driver
+ *  Based on rcar_thermal.c and work from Hien Dang and Khiem Nguyen.
+ *
+ * Copyright (C) 2016 Renesas Electronics Corporation.
+ * Copyright (C) 2016 Sang Engineering
+ *
+ *  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; version 2 of the License.
+ *
+ *  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/delay.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/thermal.h>
+
+/* Register offsets */
+#define REG_GEN3_IRQSTR         0x04
+#define REG_GEN3_IRQMSK         0x08
+#define REG_GEN3_IRQCTL         0x0C
+#define REG_GEN3_IRQEN          0x10
+#define REG_GEN3_IRQTEMP1       0x14
+#define REG_GEN3_IRQTEMP2       0x18
+#define REG_GEN3_IRQTEMP3       0x1C
+#define REG_GEN3_CTSR           0x20
+#define REG_GEN3_THCTR          0x20
+#define REG_GEN3_TEMP           0x28
+#define REG_GEN3_THCODE1        0x50
+#define REG_GEN3_THCODE2        0x54
+#define REG_GEN3_THCODE3        0x58
+
+/* CTSR bits */
+#define CTSR_PONM       BIT(8)
+#define CTSR_AOUT       BIT(7)
+#define CTSR_THBGR      BIT(5)
+#define CTSR_VMEN       BIT(4)
+#define CTSR_VMST       BIT(1)
+#define CTSR_THSST      BIT(0)
+
+/* THCTR bits */
+#define THCTR_PONM      BIT(6)
+#define THCTR_THSST     BIT(0)
+
+#define CTEMP_MASK      0xFFF
+
+#define MCELSIUS(temp)  ((temp) * 1000)
+#define GEN3_FUSE_MASK  0xFFF
+
+#define TSC_MAX_NUM     3
+
+/* Structure for thermal temperature calculation */
+struct equation_coefs {
+        int a1;
+        int b1;
+        int a2;
+        int b2;
+};
+
+struct rcar_gen3_thermal_tsc {
+        void __iomem *base;
+        struct thermal_zone_device *zone;
+        struct equation_coefs coef;
+        struct mutex lock;
+};
+
+struct rcar_gen3_thermal_priv {
+        struct rcar_gen3_thermal_tsc *tscs[TSC_MAX_NUM];
+};
+
+struct rcar_gen3_thermal_data {
+        void (*thermal_init)(struct rcar_gen3_thermal_tsc *tsc);
+};
+
+static inline u32 rcar_gen3_thermal_read(struct rcar_gen3_thermal_tsc *tsc,
+                                         u32 reg)
+{
+        return ioread32(tsc->base + reg);
+}
+
+static inline void rcar_gen3_thermal_write(struct rcar_gen3_thermal_tsc *tsc,
+                                           u32 reg, u32 data)
+{
+        iowrite32(data, tsc->base + reg);
+}
+
+/*
+ * Linear approximation for temperature
+ *
+ * [reg] = [temp] * a + b => [temp] = ([reg] - b) / a
+ *
+ * The constants a and b are calculated using two triplets of int values PTAT
+ * and THCODE. PTAT and THCODE can either be read from hardware or use hard
+ * coded values from driver. The formula to calculate a and b are taken from
+ * BSP and sparsely documented and understood.
+ *
+ * Examining the linear formula and the formula used to calculate constants a
+ * and b while knowing that the span for PTAT and THCODE values are between
+ * 0x000 and 0xfff the largest integer possible is 0xfff * 0xfff == 0xffe001.
+ * Integer also needs to be signed so that leaves 7 bits for binary
+ * fixed point scaling.
+ */
+
+#define FIXPT_SHIFT 7
+#define FIXPT_INT(_x) ((_x) << FIXPT_SHIFT)
+#define FIXPT_DIV(_a, _b) DIV_ROUND_CLOSEST(((_a) << FIXPT_SHIFT), (_b))
+#define FIXPT_TO_MCELSIUS(_x) ((_x) * 1000 >> FIXPT_SHIFT)
+
+#define RCAR3_THERMAL_GRAN 500 /* mili Celsius */
+
+/* no idea where these constants come from */
+#define TJ_1 96
+#define TJ_3 -41
+
+static void rcar_gen3_thermal_calc_coefs(struct equation_coefs *coef,
+                                         int *ptat, int *thcode)
+{
+        int tj_2;
+
+        /* TODO: Find documentation and document constant calculation formula */
+
+        /*
+         * Division is not scaled in BSP and if scaled it might overflow
+         * the dividend (4095 * 4095 << 14 > INT_MAX) so keep it unscaled
+         */
+        tj_2 = (FIXPT_INT((ptat[1] - ptat[2]) * 137)
+                / (ptat[0] - ptat[2])) - FIXPT_INT(41);
+
+        coef->a1 = FIXPT_DIV(FIXPT_INT(thcode[1] - thcode[2]),
+                             tj_2 - FIXPT_INT(TJ_3));
+        coef->b1 = FIXPT_INT(thcode[2]) - coef->a1 * TJ_3;
+
+        coef->a2 = FIXPT_DIV(FIXPT_INT(thcode[1] - thcode[0]),
+                             tj_2 - FIXPT_INT(TJ_1));
+        coef->b2 = FIXPT_INT(thcode[0]) - coef->a2 * TJ_1;
+}
+
+static int rcar_gen3_thermal_round(int temp)
+{
+        int result, round_offs;
+
+        round_offs = temp >= 0 ? RCAR3_THERMAL_GRAN / 2 :
+                -RCAR3_THERMAL_GRAN / 2;
+        result = (temp + round_offs) / RCAR3_THERMAL_GRAN;
+        return result * RCAR3_THERMAL_GRAN;
+}
+
+static int rcar_gen3_thermal_get_temp(void *devdata, int *temp)
+{
+        struct rcar_gen3_thermal_tsc *tsc = devdata;
+        int mcelsius, val1, val2;
+        u32 reg;
+
+        /* Read register and convert to mili Celsius */
+        mutex_lock(&tsc->lock);
+
+        reg = rcar_gen3_thermal_read(tsc, REG_GEN3_TEMP) & CTEMP_MASK;
+
+        val1 = FIXPT_DIV(FIXPT_INT(reg) - tsc->coef.b1, tsc->coef.a1);
+        val2 = FIXPT_DIV(FIXPT_INT(reg) - tsc->coef.b2, tsc->coef.a2);
+        mcelsius = FIXPT_TO_MCELSIUS((val1 + val2) / 2);
+
+        mutex_unlock(&tsc->lock);
+
+        /* Make sure we are inside specifications */
+        if ((mcelsius < MCELSIUS(-40)) || (mcelsius > MCELSIUS(125)))
+                return -EIO;
+
+        /* Round value to device granularity setting */
+        *temp = rcar_gen3_thermal_round(mcelsius);
+
+        return 0;
+}
+
+static struct thermal_zone_of_device_ops rcar_gen3_tz_of_ops = {
+        .get_temp       = rcar_gen3_thermal_get_temp,
+};
+
+static void r8a7795_thermal_init(struct rcar_gen3_thermal_tsc *tsc)
+{
+        rcar_gen3_thermal_write(tsc, REG_GEN3_CTSR,  CTSR_THBGR);
+        rcar_gen3_thermal_write(tsc, REG_GEN3_CTSR,  0x0);
+
+        usleep_range(1000, 2000);
+
+        rcar_gen3_thermal_write(tsc, REG_GEN3_CTSR, CTSR_PONM);
+        rcar_gen3_thermal_write(tsc, REG_GEN3_IRQCTL, 0x3F);
+        rcar_gen3_thermal_write(tsc, REG_GEN3_CTSR,
+                                CTSR_PONM | CTSR_AOUT | CTSR_THBGR | CTSR_VMEN);
+
+        usleep_range(100, 200);
+
+        rcar_gen3_thermal_write(tsc, REG_GEN3_CTSR,
+                                CTSR_PONM | CTSR_AOUT | CTSR_THBGR | CTSR_VMEN |
+                                CTSR_VMST | CTSR_THSST);
+
+        usleep_range(1000, 2000);
+}
+
+static void r8a7796_thermal_init(struct rcar_gen3_thermal_tsc *tsc)
+{
+        u32 reg_val;
+
+        reg_val = rcar_gen3_thermal_read(tsc, REG_GEN3_THCTR);
+        reg_val &= ~THCTR_PONM;
+        rcar_gen3_thermal_write(tsc, REG_GEN3_THCTR, reg_val);
+
+        usleep_range(1000, 2000);
+
+        rcar_gen3_thermal_write(tsc, REG_GEN3_IRQCTL, 0x3F);
+        reg_val = rcar_gen3_thermal_read(tsc, REG_GEN3_THCTR);
+        reg_val |= THCTR_THSST;
+        rcar_gen3_thermal_write(tsc, REG_GEN3_THCTR, reg_val);
+}
+
+static const struct rcar_gen3_thermal_data r8a7795_data = {
+        .thermal_init = r8a7795_thermal_init,
+};
+
+static const struct rcar_gen3_thermal_data r8a7796_data = {
+        .thermal_init = r8a7796_thermal_init,
+};
+
+static const struct of_device_id rcar_gen3_thermal_dt_ids[] = {
+        { .compatible = "renesas,r8a7795-thermal", .data = &r8a7795_data},
+        { .compatible = "renesas,r8a7796-thermal", .data = &r8a7796_data},
+        {},
+};
+MODULE_DEVICE_TABLE(of, rcar_gen3_thermal_dt_ids);
+
+static int rcar_gen3_thermal_remove(struct platform_device *pdev)
+{
+        struct device *dev = &pdev->dev;
+
+        pm_runtime_put(dev);
+        pm_runtime_disable(dev);
+
+        return 0;
+}
+
+static int rcar_gen3_thermal_probe(struct platform_device *pdev)
+{
+        struct rcar_gen3_thermal_priv *priv;
+        struct device *dev = &pdev->dev;
+        struct resource *res;
+        struct thermal_zone_device *zone;
+        int ret, i;
+        const struct rcar_gen3_thermal_data *match_data =
+                of_device_get_match_data(dev);
+
+        /* default values if FUSEs are missing */
+        /* TODO: Read values from hardware on supported platforms */
+        int ptat[3] = { 2351, 1509, 435 };
+        int thcode[TSC_MAX_NUM][3] = {
+                { 3248, 2800, 2221 },
+                { 3245, 2795, 2216 },
+                { 3250, 2805, 2237 },
+        };
+
+        priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+        if (!priv)
+                return -ENOMEM;
+
+        platform_set_drvdata(pdev, priv);
+
+        pm_runtime_enable(dev);
+        pm_runtime_get_sync(dev);
+
+        for (i = 0; i < TSC_MAX_NUM; i++) {
+                struct rcar_gen3_thermal_tsc *tsc;
+
+                tsc = devm_kzalloc(dev, sizeof(*tsc), GFP_KERNEL);
+                if (!tsc) {
+                        ret = -ENOMEM;
+                        goto error_unregister;
+                }
+
+                res = platform_get_resource(pdev, IORESOURCE_MEM, i);
+                if (!res)
+                        break;
+
+                tsc->base = devm_ioremap_resource(dev, res);
+                if (IS_ERR(tsc->base)) {
+                        ret = PTR_ERR(tsc->base);
+                        goto error_unregister;
+                }
+
+                priv->tscs[i] = tsc;
+                mutex_init(&tsc->lock);
+
+                match_data->thermal_init(tsc);
+                rcar_gen3_thermal_calc_coefs(&tsc->coef, ptat, thcode[i]);
+
+                zone = devm_thermal_zone_of_sensor_register(dev, i, tsc,
+                                                            &rcar_gen3_tz_of_ops);
+                if (IS_ERR(zone)) {
+                        dev_err(dev, "Can't register thermal zone\n");
+                        ret = PTR_ERR(zone);
+                        goto error_unregister;
+                }
+                tsc->zone = zone;
+        }
+
+        return 0;
+
+error_unregister:
+        rcar_gen3_thermal_remove(pdev);
+
+        return ret;
+}
+
+static struct platform_driver rcar_gen3_thermal_driver = {
+        .driver = {
+                .name   = "rcar_gen3_thermal",
+                .of_match_table = rcar_gen3_thermal_dt_ids,
+        },
+        .probe          = rcar_gen3_thermal_probe,
+        .remove         = rcar_gen3_thermal_remove,
+};
+module_platform_driver(rcar_gen3_thermal_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("R-Car Gen3 THS thermal sensor driver");
+MODULE_AUTHOR("Wolfram Sang <wsa+renesas@sang-engineering.com>");