drm/tinydrm: Move tinydrm_spi_transfer()

This is only used by mipi-dbi drivers so move it there.

The reason this isn't moved to the SPI subsystem is that it will in a
later patch pass a dummy rx buffer for SPI controllers that need this.
Low memory boards (64MB) can run into a problem allocating such a "large"
contiguous buffer on every transfer after a long up time.
This leaves a very specific use case, so we'll keep the function here.
mipi-dbi will first go through a refactoring though, before this will
be done.

Remove SPI todo entry now that we're done with the tinydrm.ko SPI code.

v2: Drop moving the mipi_dbi_spi_init() declaration (Sam)

Cc: David Lechner <david@lechnology.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Acked-by: : David Lechner <david@lechnology.com>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20190719155916.62465-8-noralf@tronnes.org

Documentation/gpu/tinydrm.rst

@@ -11,9 +11,6 @@ Helpers
 .. kernel-doc:: include/drm/tinydrm/tinydrm-helpers.h
    :internal:
 
-.. kernel-doc:: drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c
-   :export:
-
 .. kernel-doc:: drivers/gpu/drm/tinydrm/core/tinydrm-pipe.c
    :export:
 

Documentation/gpu/todo.rst

@@ -443,9 +443,6 @@ tinydrm
 Tinydrm is the helper driver for really simple fb drivers. The goal is to make
 those drivers as simple as possible, so lots of room for refactoring:
 
-- spi helpers, probably best put into spi core/helper code. Thierry said
-  the spi maintainer is fast&reactive, so shouldn't be a big issue.
-
 - extract the mipi-dbi helper (well, the non-tinydrm specific parts at
   least) into a separate helper, like we have for mipi-dsi already. Or follow
   one of the ideas for having a shared dsi/dbi helper, abstracting away the

drivers/gpu/drm/tinydrm/core/Makefile

 # SPDX-License-Identifier: GPL-2.0-only
-tinydrm-y := tinydrm-pipe.o tinydrm-helpers.o
+tinydrm-y := tinydrm-pipe.o
 
 obj-$(CONFIG_DRM_TINYDRM) += tinydrm.o

drivers/gpu/drm/tinydrm/core/tinydrm-helpers.c

-// SPDX-License-Identifier: GPL-2.0-or-later
-/*
- * Copyright (C) 2016 Noralf Trønnes
- */
-
-#include <linux/backlight.h>
-#include <linux/dma-buf.h>
-#include <linux/module.h>
-#include <linux/pm.h>
-#include <linux/spi/spi.h>
-#include <linux/swab.h>
-
-#include <drm/drm_device.h>
-#include <drm/drm_drv.h>
-#include <drm/drm_fourcc.h>
-#include <drm/drm_framebuffer.h>
-#include <drm/drm_print.h>
-#include <drm/drm_rect.h>
-#include <drm/tinydrm/tinydrm-helpers.h>
-
-#if IS_ENABLED(CONFIG_SPI)
-
-/**
- * tinydrm_spi_transfer - SPI transfer helper
- * @spi: SPI device
- * @speed_hz: Override speed (optional)
- * @bpw: Bits per word
- * @buf: Buffer to transfer
- * @len: Buffer length
- *
- * This SPI transfer helper breaks up the transfer of @buf into chunks which
- * the SPI controller driver can handle.
- *
- * Returns:
- * Zero on success, negative error code on failure.
- */
-int tinydrm_spi_transfer(struct spi_device *spi, u32 speed_hz,
-			 u8 bpw, const void *buf, size_t len)
-{
-	size_t max_chunk = spi_max_transfer_size(spi);
-	struct spi_transfer tr = {
-		.bits_per_word = bpw,
-		.speed_hz = speed_hz,
-	};
-	struct spi_message m;
-	size_t chunk;
-	int ret;
-
-	spi_message_init_with_transfers(&m, &tr, 1);
-
-	while (len) {
-		chunk = min(len, max_chunk);
-
-		tr.tx_buf = buf;
-		tr.len = chunk;
-		buf += chunk;
-		len -= chunk;
-
-		ret = spi_sync(spi, &m);
-		if (ret)
-			return ret;
-	}
-
-	return 0;
-}
-EXPORT_SYMBOL(tinydrm_spi_transfer);
-
-#endif /* CONFIG_SPI */
-
-MODULE_LICENSE("GPL");

drivers/gpu/drm/tinydrm/core/tinydrm-pipe.c

@@ -3,6 +3,8 @@
  * Copyright (C) 2016 Noralf Trønnes
  */
 
+#include <linux/module.h>
+
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_drv.h>
 #include <drm/drm_gem_framebuffer_helper.h>
@@ -177,3 +179,5 @@ int tinydrm_display_pipe_init(struct drm_device *drm,
 					    format_count, modifiers, connector);
 }
 EXPORT_SYMBOL(tinydrm_display_pipe_init);
+
+MODULE_LICENSE("GPL");

drivers/gpu/drm/tinydrm/ili9225.c

@@ -27,7 +27,6 @@
 #include <drm/drm_rect.h>
 #include <drm/drm_vblank.h>
 #include <drm/tinydrm/mipi-dbi.h>
-#include <drm/tinydrm/tinydrm-helpers.h>
 
 #define ILI9225_DRIVER_READ_CODE	0x00
 #define ILI9225_DRIVER_OUTPUT_CONTROL	0x01
@@ -323,7 +322,7 @@ static int ili9225_dbi_command(struct mipi_dbi *mipi, u8 *cmd, u8 *par,
 
 	gpiod_set_value_cansleep(mipi->dc, 0);
 	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, 1);
-	ret = tinydrm_spi_transfer(spi, speed_hz, 8, cmd, 1);
+	ret = mipi_dbi_spi_transfer(spi, speed_hz, 8, cmd, 1);
 	if (ret || !num)
 		return ret;
 
@@ -333,7 +332,7 @@ static int ili9225_dbi_command(struct mipi_dbi *mipi, u8 *cmd, u8 *par,
 	gpiod_set_value_cansleep(mipi->dc, 1);
 	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, num);
 
-	return tinydrm_spi_transfer(spi, speed_hz, bpw, par, num);
+	return mipi_dbi_spi_transfer(spi, speed_hz, bpw, par, num);
 }
 
 static const struct drm_simple_display_pipe_funcs ili9225_pipe_funcs = {

drivers/gpu/drm/tinydrm/mipi-dbi.c

@@ -926,7 +926,7 @@ static int mipi_dbi_typec3_command(struct mipi_dbi *mipi, u8 *cmd,
 
 	gpiod_set_value_cansleep(mipi->dc, 0);
 	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, 1);
-	ret = tinydrm_spi_transfer(spi, speed_hz, 8, cmd, 1);
+	ret = mipi_dbi_spi_transfer(spi, speed_hz, 8, cmd, 1);
 	if (ret || !num)
 		return ret;
 
@@ -936,7 +936,7 @@ static int mipi_dbi_typec3_command(struct mipi_dbi *mipi, u8 *cmd,
 	gpiod_set_value_cansleep(mipi->dc, 1);
 	speed_hz = mipi_dbi_spi_cmd_max_speed(spi, num);
 
-	return tinydrm_spi_transfer(spi, speed_hz, bpw, par, num);
+	return mipi_dbi_spi_transfer(spi, speed_hz, bpw, par, num);
 }
 
 /**
@@ -1007,6 +1007,51 @@ int mipi_dbi_spi_init(struct spi_device *spi, struct mipi_dbi *mipi,
 }
 EXPORT_SYMBOL(mipi_dbi_spi_init);
 
+/**
+ * mipi_dbi_spi_transfer - SPI transfer helper
+ * @spi: SPI device
+ * @speed_hz: Override speed (optional)
+ * @bpw: Bits per word
+ * @buf: Buffer to transfer
+ * @len: Buffer length
+ *
+ * This SPI transfer helper breaks up the transfer of @buf into chunks which
+ * the SPI controller driver can handle.
+ *
+ * Returns:
+ * Zero on success, negative error code on failure.
+ */
+int mipi_dbi_spi_transfer(struct spi_device *spi, u32 speed_hz,
+			  u8 bpw, const void *buf, size_t len)
+{
+	size_t max_chunk = spi_max_transfer_size(spi);
+	struct spi_transfer tr = {
+		.bits_per_word = bpw,
+		.speed_hz = speed_hz,
+	};
+	struct spi_message m;
+	size_t chunk;
+	int ret;
+
+	spi_message_init_with_transfers(&m, &tr, 1);
+
+	while (len) {
+		chunk = min(len, max_chunk);
+
+		tr.tx_buf = buf;
+		tr.len = chunk;
+		buf += chunk;
+		len -= chunk;
+
+		ret = spi_sync(spi, &m);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(mipi_dbi_spi_transfer);
+
 #endif /* CONFIG_SPI */
 
 #ifdef CONFIG_DEBUG_FS

include/drm/tinydrm/mipi-dbi.h

@@ -83,7 +83,10 @@ void mipi_dbi_hw_reset(struct mipi_dbi *mipi);
 bool mipi_dbi_display_is_on(struct mipi_dbi *mipi);
 int mipi_dbi_poweron_reset(struct mipi_dbi *mipi);
 int mipi_dbi_poweron_conditional_reset(struct mipi_dbi *mipi);
+
 u32 mipi_dbi_spi_cmd_max_speed(struct spi_device *spi, size_t len);
+int mipi_dbi_spi_transfer(struct spi_device *spi, u32 speed_hz,
+			  u8 bpw, const void *buf, size_t len);
 
 int mipi_dbi_command_read(struct mipi_dbi *mipi, u8 cmd, u8 *val);
 int mipi_dbi_command_buf(struct mipi_dbi *mipi, u8 cmd, u8 *data, size_t len);

include/drm/tinydrm/tinydrm-helpers.h

@@ -13,8 +13,6 @@ struct drm_framebuffer;
 struct drm_rect;
 struct drm_simple_display_pipe;
 struct drm_simple_display_pipe_funcs;
-struct spi_transfer;
-struct spi_device;
 struct device;
 
 /**
@@ -41,7 +39,4 @@ int tinydrm_display_pipe_init(struct drm_device *drm,
 			      const struct drm_display_mode *mode,
 			      unsigned int rotation);
 
-int tinydrm_spi_transfer(struct spi_device *spi, u32 speed_hz,
-			 u8 bpw, const void *buf, size_t len);
-
 #endif /* __LINUX_TINYDRM_HELPERS_H */