drm: atmel-hlcdc: add config option for clock selection

SAM9x60 LCD Controller has no option to select clock source as previous
controllers have. To be able to use the same driver even for this LCD
controller add a config option to know if controller supports this.
Signed-off-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1556195748-11106-2-git-send-email-claudiu.beznea@microchip.com

drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_crtc.c

@@ -78,7 +78,8 @@ static void atmel_hlcdc_crtc_mode_set_nofb(struct drm_crtc *c)
 	unsigned long mode_rate;
 	struct videomode vm;
 	unsigned long prate;
-	unsigned int cfg;
+	unsigned int mask = ATMEL_HLCDC_CLKDIV_MASK | ATMEL_HLCDC_CLKPOL;
+	unsigned int cfg = 0;
 	int div;
 
 	vm.vfront_porch = adj->crtc_vsync_start - adj->crtc_vdisplay;
@@ -101,7 +102,10 @@ static void atmel_hlcdc_crtc_mode_set_nofb(struct drm_crtc *c)
 		     (adj->crtc_hdisplay - 1) |
 		     ((adj->crtc_vdisplay - 1) << 16));
 
-	cfg = ATMEL_HLCDC_CLKSEL;
+	if (!crtc->dc->desc->fixed_clksrc) {
+		cfg |= ATMEL_HLCDC_CLKSEL;
+		mask |= ATMEL_HLCDC_CLKSEL;
+	}
 
 	prate = 2 * clk_get_rate(crtc->dc->hlcdc->sys_clk);
 	mode_rate = adj->crtc_clock * 1000;
@@ -132,9 +136,7 @@ static void atmel_hlcdc_crtc_mode_set_nofb(struct drm_crtc *c)
 
 	cfg |= ATMEL_HLCDC_CLKDIV(div);
 
-	regmap_update_bits(regmap, ATMEL_HLCDC_CFG(0),
-			   ATMEL_HLCDC_CLKSEL | ATMEL_HLCDC_CLKDIV_MASK |
-			   ATMEL_HLCDC_CLKPOL, cfg);
+	regmap_update_bits(regmap, ATMEL_HLCDC_CFG(0), mask, cfg);
 
 	cfg = 0;
 

drivers/gpu/drm/atmel-hlcdc/atmel_hlcdc_dc.h

@@ -328,6 +328,7 @@ atmel_hlcdc_layer_to_plane(struct atmel_hlcdc_layer *layer)
  * @max_hpw: maximum horizontal back/front porch width
  * @conflicting_output_formats: true if RGBXXX output formats conflict with
  *				each other.
+ * @fixed_clksrc: true if clock source is fixed
  * @layers: a layer description table describing available layers
  * @nlayers: layer description table size
  */
@@ -340,6 +341,7 @@ struct atmel_hlcdc_dc_desc {
 	int max_vpw;
 	int max_hpw;
 	bool conflicting_output_formats;
+	bool fixed_clksrc;
 	const struct atmel_hlcdc_layer_desc *layers;
 	int nlayers;
 };