Add SMI driver

Signed-off-by: Luke Wren <wren6991@gmail.com>

MISC: bcm2835: smi: use clock manager and fix reload issues

Use clock manager instead of self-made clockmanager.

Also fix some error paths that showd up during development
(especially missing release of dma resources on rmmod)

Signed-off-by: Martin Sperl <kernel@martin.sperl.org>

bcm2835_smi: re-add dereference to fix DMA transfers

bcm2835_smi_dev: Fix handling of word-odd lengths

The read and write functions did not use the correct pointer offset
when dealing with an odd number of bytes after a DMA transfer. Also,
only handle the remaining odd bytes if the DMA transfer completed
successfully.

Submitted-by: @madimario (GitHub)
Signed-off-by: Phil Elwell <phil@raspberrypi.com>

misc: bcm2835_smi: Use proper enum types for dma_{,un}map_single()

Clang warns:

  drivers/misc/bcm2835_smi.c:692:4: warning: implicit conversion from enumeration type 'enum dma_transfer_direction' to different enumeration type 'enum dma_data_direction' [-Wenum-conversion]
                          DMA_MEM_TO_DEV);
                          ^~~~~~~~~~~~~~~
  ./include/linux/dma-mapping.h:406:66: note: expanded from macro 'dma_map_single'
  #define dma_map_single(d, a, s, r) dma_map_single_attrs(d, a, s, r, 0)
                                     ~~~~~~~~~~~~~~~~~~~~          ^
  drivers/misc/bcm2835_smi.c:705:35: warning: implicit conversion from enumeration type 'enum dma_transfer_direction' to different enumeration type 'enum dma_data_direction' [-Wenum-conversion]
                          (inst->dev, phy_addr, n_bytes, DMA_MEM_TO_DEV);
                          ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
  ./include/linux/dma-mapping.h:407:70: note: expanded from macro 'dma_unmap_single'
  #define dma_unmap_single(d, a, s, r) dma_unmap_single_attrs(d, a, s, r, 0)
                                       ~~~~~~~~~~~~~~~~~~~~~~          ^
  drivers/misc/bcm2835_smi.c:751:12: warning: implicit conversion from enumeration type 'enum dma_transfer_direction' to different enumeration type 'enum dma_data_direction' [-Wenum-conversion]
                                                       DMA_DEV_TO_MEM);
                                                       ^~~~~~~~~~~~~~~
  ./include/linux/dma-mapping.h:406:66: note: expanded from macro 'dma_map_single'
  #define dma_map_single(d, a, s, r) dma_map_single_attrs(d, a, s, r, 0)
                                     ~~~~~~~~~~~~~~~~~~~~          ^
  drivers/misc/bcm2835_smi.c:761:50: warning: implicit conversion from enumeration type 'enum dma_transfer_direction' to different enumeration type 'enum dma_data_direction' [-Wenum-conversion]
                  dma_unmap_single(inst->dev, phy_addr, n_bytes, DMA_DEV_TO_MEM);
                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~
  ./include/linux/dma-mapping.h:407:70: note: expanded from macro 'dma_unmap_single'
  #define dma_unmap_single(d, a, s, r) dma_unmap_single_attrs(d, a, s, r, 0)
                                       ~~~~~~~~~~~~~~~~~~~~~~          ^
  4 warnings generated.

Use the proper enumerated type to clear up the warning. There is not
actually a bug here because the enumerated types have the same integer
value:

DMA_MEM_TO_DEV = DMA_TO_DEVICE = 1
DMA_DEV_TO_MEM = DMA_FROM_DEVICE = 2

Fixes: 93254d0 ("Add SMI driver")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>

bcm2835-smi: Use phys addresses for slave DMA config

Contrary to what struct snd_dmaengine_dai_dma_data suggests, the
configuration of addresses of DMA slave interfaces should be done in
CPU physical addresses.

Signed-off-by: Phil Elwell <phil@raspberrypi.com>

Documentation/devicetree/bindings/misc/brcm,bcm2835-smi-dev.txt

@@ -0,0 +1,17 @@
+* Broadcom BCM2835 SMI character device driver.
+
+SMI or secondary memory interface is a peripheral specific to certain Broadcom
+SOCs, and is helpful for talking to things like parallel-interface displays
+and NAND flashes (in fact, most things with a parallel register interface).
+
+This driver adds a character device which provides a user-space interface to
+an instance of the SMI driver.
+
+Required properties:
+- compatible: "brcm,bcm2835-smi-dev"
+- smi_handle: a phandle to the smi node.
+
+Optional properties:
+- None.
+
+

Documentation/devicetree/bindings/misc/brcm,bcm2835-smi.txt

@@ -0,0 +1,48 @@
+* Broadcom BCM2835 SMI driver.
+
+SMI or secondary memory interface is a peripheral specific to certain Broadcom
+SOCs, and is helpful for talking to things like parallel-interface displays
+and NAND flashes (in fact, most things with a parallel register interface).
+
+Required properties:
+- compatible: "brcm,bcm2835-smi"
+- reg: Should contain location and length of SMI registers and SMI clkman regs
+- interrupts: *the* SMI interrupt.
+- pinctrl-names: should be "default".
+- pinctrl-0: the phandle of the gpio pin node.
+- brcm,smi-clock-source: the clock source for clkman
+- brcm,smi-clock-divisor: the integer clock divisor for clkman
+- dmas: the dma controller phandle and the DREQ number (4 on a 2835)
+- dma-names: the name used by the driver to request its channel.
+  Should be "rx-tx".
+
+Optional properties:
+- None.
+
+Examples:
+
+8 data pin configuration:
+
+smi: smi@7e600000 {
+	compatible = "brcm,bcm2835-smi";
+	reg = <0x7e600000 0x44>, <0x7e1010b0 0x8>;
+	interrupts = <2 16>;
+	pinctrl-names = "default";
+	pinctrl-0 = <&smi_pins>;
+	brcm,smi-clock-source = <6>;
+	brcm,smi-clock-divisor = <4>;
+	dmas = <&dma 4>;
+	dma-names = "rx-tx";
+
+	status = "okay";
+};
+
+smi_pins: smi_pins {
+	brcm,pins = <2 3 4 5 6 7 8 9 10 11 12 13 14 15>;
+	/* Alt 1: SMI */
+	brcm,function = <5 5 5 5 5 5 5 5 5 5 5 5 5 5>;
+	/* /CS, /WE and /OE are pulled high, as they are
+	   generally active low signals */
+	brcm,pull = <2 2 2 2 2 2 0 0 0 0 0 0 0 0>;
+};
+

drivers/char/broadcom/Kconfig

@@ -24,3 +24,12 @@ config BCM2835_DEVGPIOMEM
 		Provides users with root-free access to the GPIO registers
 		on the 2835. Calling mmap(/dev/gpiomem) will map the GPIO
 		register page to the user's pointer.
+
+config BCM2835_SMI_DEV
+	tristate "Character device driver for BCM2835 Secondary Memory Interface"
+	depends on BCM2835_SMI
+	default m
+	help
+		This driver provides a character device interface (ioctl + read/write) to
+		Broadcom's Secondary Memory interface. The low-level functionality is provided
+		by the SMI driver itself.

drivers/char/broadcom/Makefile

@@ -1,2 +1,3 @@
 obj-$(CONFIG_BCM2708_VCMEM)	+= vc_mem.o
 obj-$(CONFIG_BCM2835_DEVGPIOMEM)+= bcm2835-gpiomem.o
+obj-$(CONFIG_BCM2835_SMI_DEV)	+= bcm2835_smi_dev.o