drm/radeon/dpm: add debugfs support for RS780/RS880 (v3)

This allows you to look at the current DPM state via
debugfs.

Due to the way the hardware works on these asics, there's
no way to look up exactly what power state we are in, so
we make the best guess we can based on the current sclk.

v2: Anthoine's version
v3: fix ref div

Signed-off-by: Alex Deucher <[e-mail]>

drivers/gpu/drm/radeon/radeon_asic.c

···
 		.get_sclk = &rs780_dpm_get_sclk,
 		.get_mclk = &rs780_dpm_get_mclk,
 		.print_power_state = &rs780_dpm_print_power_state,
+		.debugfs_print_current_performance_level = &rs780_dpm_debugfs_print_current_performance_level,
 	},
 	.pflip = {
 		.pre_page_flip = &rs600_pre_page_flip,

drivers/gpu/drm/radeon/radeon_asic.h

···
 u32 rs780_dpm_get_mclk(struct radeon_device *rdev, bool low);
 void rs780_dpm_print_power_state(struct radeon_device *rdev,
 				 struct radeon_ps *ps);
+void rs780_dpm_debugfs_print_current_performance_level(struct radeon_device *rdev,
+						       struct seq_file *m);
 
 /* uvd */
 int r600_uvd_init(struct radeon_device *rdev);

drivers/gpu/drm/radeon/rs780_dpm.c

···
 #include "r600_dpm.h"
 #include "rs780_dpm.h"
 #include "atom.h"
+#include <linux/seq_file.h>
 
 static struct igp_ps *rs780_get_ps(struct radeon_ps *rps)
 {
···
 	struct igp_power_info *pi = rs780_get_pi(rdev);
 
 	return pi->bootup_uma_clk;
+}
+
+void rs780_dpm_debugfs_print_current_performance_level(struct radeon_device *rdev,
+						       struct seq_file *m)
+{
+	struct radeon_ps *rps = rdev->pm.dpm.current_ps;
+	struct igp_ps *ps = rs780_get_ps(rps);
+	u32 current_fb_div = RREG32(FVTHROT_STATUS_REG0) & CURRENT_FEEDBACK_DIV_MASK;
+	u32 func_cntl = RREG32(CG_SPLL_FUNC_CNTL);
+	u32 ref_div = ((func_cntl & SPLL_REF_DIV_MASK) >> SPLL_REF_DIV_SHIFT) + 1;
+	u32 post_div = ((func_cntl & SPLL_SW_HILEN_MASK) >> SPLL_SW_HILEN_SHIFT) + 1 +
+		((func_cntl & SPLL_SW_LOLEN_MASK) >> SPLL_SW_LOLEN_SHIFT) + 1;
+	u32 sclk = (rdev->clock.spll.reference_freq * current_fb_div) /
+		(post_div * ref_div);
+
+	seq_printf(m, "uvd    vclk: %d dclk: %d\n", rps->vclk, rps->dclk);
+
+	/* guess based on the current sclk */
+	if (sclk < (ps->sclk_low + 500))
+		seq_printf(m, "power level 0    sclk: %u vddc_index: %d\n",
+			   ps->sclk_low, ps->min_voltage);
+	else
+		seq_printf(m, "power level 1    sclk: %u vddc_index: %d\n",
+			   ps->sclk_high, ps->max_voltage);
 }

drivers/gpu/drm/radeon/rs780d.h

···
 #       define SPLL_SLEEP                                (1 << 1)
 #       define SPLL_REF_DIV(x)                           ((x) << 2)
 #       define SPLL_REF_DIV_MASK                         (7 << 2)
+#       define SPLL_REF_DIV_SHIFT                        2
 #       define SPLL_FB_DIV(x)                            ((x) << 5)
 #       define SPLL_FB_DIV_MASK                          (0xff << 2)
 #       define SPLL_FB_DIV_SHIFT                         2
···
 #       define SPLL_PULSENUM_MASK                        (3 << 14)
 #       define SPLL_SW_HILEN(x)                          ((x) << 16)
 #       define SPLL_SW_HILEN_MASK                        (0xf << 16)
+#       define SPLL_SW_HILEN_SHIFT                       16
 #       define SPLL_SW_LOLEN(x)                          ((x) << 20)
 #       define SPLL_SW_LOLEN_MASK                        (0xf << 20)
+#       define SPLL_SW_LOLEN_SHIFT                       20
 #       define SPLL_DIVEN                                (1 << 24)
 #       define SPLL_BYPASS_EN                            (1 << 25)
 #       define SPLL_CHG_STATUS                           (1 << 29)