[PATCH 3/8] devfreq: rk3399_dmc: Pass ODT and auto power down parameters to TF-A.

[Enric Balletbo i Serra]

Trusted Firmware-A (TF-A) for rk3399 implements a SiP call to get the
on-die termination (ODT) and auto power down parameters from kernel,
this patch adds the functionality to do this. Also, if DDR clock
frequency is lower than the on-die termination (ODT) disable frequency
this driver should disable the DDR ODT.

Signed-off-by: Enric Balletbo i Serra <enric.balletbo@xxxxxxxxxxxxx>
---

Changes in v1:
- [RFC 3/10] Add an explanation for platform SIP calls.
- [RFC 3/10] Change if statement for a switch.
- [RFC 3/10] Rename ddr_flag to odt_enable to be more clear.

 drivers/devfreq/rk3399_dmc.c        | 74 ++++++++++++++++++++++++++++-
 include/soc/rockchip/rockchip_sip.h |  1 +
 2 files changed, 74 insertions(+), 1 deletion(-)

diff --git a/drivers/devfreq/rk3399_dmc.c b/drivers/devfreq/rk3399_dmc.c
index e795ad2b3f6b..c619dc4ac620 100644
--- a/drivers/devfreq/rk3399_dmc.c
+++ b/drivers/devfreq/rk3399_dmc.c
@@ -18,14 +18,17 @@
 #include <linux/devfreq.h>
 #include <linux/devfreq-event.h>
 #include <linux/interrupt.h>
+#include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/platform_device.h>
 #include <linux/pm_opp.h>
+#include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
 #include <linux/rwsem.h>
 #include <linux/suspend.h>
 
+#include <soc/rockchip/rk3399_grf.h>
 #include <soc/rockchip/rockchip_sip.h>
 
 struct dram_timing {
@@ -69,8 +72,11 @@ struct rk3399_dmcfreq {
 	struct mutex lock;
 	struct dram_timing timing;
 	struct regulator *vdd_center;
+	struct regmap *regmap_pmu;
 	unsigned long rate, target_rate;
 	unsigned long volt, target_volt;
+	unsigned int odt_dis_freq;
+	int odt_pd_arg0, odt_pd_arg1;
 };
 
 static int rk3399_dmcfreq_target(struct device *dev, unsigned long *freq,
@@ -80,6 +86,8 @@ static int rk3399_dmcfreq_target(struct device *dev, unsigned long *freq,
 	struct dev_pm_opp *opp;
 	unsigned long old_clk_rate = dmcfreq->rate;
 	unsigned long target_volt, target_rate;
+	struct arm_smccc_res res;
+	bool odt_enable = false;
 	int err;
 
 	opp = devfreq_recommended_opp(dev, freq, flags);
@@ -95,6 +103,19 @@ static int rk3399_dmcfreq_target(struct device *dev, unsigned long *freq,
 
 	mutex_lock(&dmcfreq->lock);
 
+	if (target_rate >= dmcfreq->odt_dis_freq)
+		odt_enable = true;
+
+	/*
+	 * This makes a SMC call to the TF-A to set the DDR PD (power-down)
+	 * timings and to enable or disable the ODT (on-die termination)
+	 * resistors.
+	 */
+	arm_smccc_smc(ROCKCHIP_SIP_DRAM_FREQ, dmcfreq->odt_pd_arg0,
+		      dmcfreq->odt_pd_arg1,
+		      ROCKCHIP_SIP_CONFIG_DRAM_SET_ODT_PD,
+		      odt_enable, 0, 0, 0, &res);
+
 	/*
 	 * If frequency scaling from low to high, adjust voltage first.
 	 * If frequency scaling from high to low, adjust frequency first.
@@ -294,11 +315,13 @@ static int rk3399_dmcfreq_probe(struct platform_device *pdev)
 {
 	struct arm_smccc_res res;
 	struct device *dev = &pdev->dev;
-	struct device_node *np = pdev->dev.of_node;
+	struct device_node *np = pdev->dev.of_node, *node;
 	struct rk3399_dmcfreq *data;
 	int ret, index, size;
 	uint32_t *timing;
 	struct dev_pm_opp *opp;
+	u32 ddr_type;
+	u32 val;
 
 	data = devm_kzalloc(dev, sizeof(struct rk3399_dmcfreq), GFP_KERNEL);
 	if (!data)
@@ -334,6 +357,34 @@ static int rk3399_dmcfreq_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	/* Try to find the optional reference to the pmu syscon */
+	node = of_parse_phandle(np, "rockchip,pmu", 0);
+	if (node) {
+		data->regmap_pmu = syscon_node_to_regmap(node);
+		if (IS_ERR(data->regmap_pmu))
+			return PTR_ERR(data->regmap_pmu);
+	}
+
+	/* Get DDR type */
+	regmap_read(data->regmap_pmu, RK3399_PMUGRF_OS_REG2, &val);
+	ddr_type = (val >> RK3399_PMUGRF_DDRTYPE_SHIFT) &
+		    RK3399_PMUGRF_DDRTYPE_MASK;
+
+	/* Get the odt_dis_freq parameter in function of the DDR type */
+	switch (ddr_type) {
+	case RK3399_PMUGRF_DDRTYPE_DDR3:
+		data->odt_dis_freq = data->timing.ddr3_odt_dis_freq;
+		break;
+	case RK3399_PMUGRF_DDRTYPE_LPDDR3:
+		data->odt_dis_freq = data->timing.lpddr3_odt_dis_freq;
+		break;
+	case RK3399_PMUGRF_DDRTYPE_LPDDR4:
+		data->odt_dis_freq = data->timing.lpddr4_odt_dis_freq;
+		break;
+	default:
+		return -EINVAL;
+	};
+
 	/*
 	 * Get dram timing and pass it to arm trust firmware,
 	 * the dram drvier in arm trust firmware will get these
@@ -358,6 +409,27 @@ static int rk3399_dmcfreq_probe(struct platform_device *pdev)
 		      ROCKCHIP_SIP_CONFIG_DRAM_INIT,
 		      0, 0, 0, 0, &res);
 
+	/*
+	 * In TF-A there is a platform SIP call to set the PD (power-down)
+	 * timings and to enable or disable the ODT (on-die termination).
+	 * This call needs three arguments as follows:
+	 *
+	 * arg0:
+	 *     bit[0-7]   : sr_idle
+	 *     bit[8-15]  : sr_mc_gate_idle
+	 *     bit[16-31] : standby idle
+	 * arg1:
+	 *     bit[0-11]  : pd_idle
+	 *     bit[16-27] : srpd_lite_idle
+	 * arg2:
+	 *     bit[0]     : odt enable
+	 */
+	data->odt_pd_arg0 = (data->timing.sr_idle & 0xff) |
+			    ((data->timing.sr_mc_gate_idle & 0xff) << 8) |
+			    ((data->timing.standby_idle & 0xffff) << 16);
+	data->odt_pd_arg1 = (data->timing.pd_idle & 0xfff) |
+			    ((data->timing.srpd_lite_idle & 0xfff) << 16);
+
 	/*
 	 * We add a devfreq driver to our parent since it has a device tree node
 	 * with operating points.
diff --git a/include/soc/rockchip/rockchip_sip.h b/include/soc/rockchip/rockchip_sip.h
index 7e28092c4d3d..ad9482c56797 100644
--- a/include/soc/rockchip/rockchip_sip.h
+++ b/include/soc/rockchip/rockchip_sip.h
@@ -23,5 +23,6 @@
 #define ROCKCHIP_SIP_CONFIG_DRAM_GET_RATE	0x05
 #define ROCKCHIP_SIP_CONFIG_DRAM_CLR_IRQ	0x06
 #define ROCKCHIP_SIP_CONFIG_DRAM_SET_PARAM	0x07
+#define ROCKCHIP_SIP_CONFIG_DRAM_SET_ODT_PD	0x08
 
 #endif
-- 
2.18.0