[PATCH v9 0/3] i2c: imx: add DMA support for freescale i2c driver

[PATCH v9 0/3] i2c: imx: add DMA support for freescale i2c driver

[Yuan Yao]

Changed in v9: 
- seperate a patch for sort include headers alphabetically 
- some minor fixes for coding style. 

Changed in v8: 
- some minor fixes for coding style. 
- unsetting I2CR_DMAEN immediatelly when DMA failed. 

Changed in v7: 
- when waiting for transfer complete use schedule() instead of udelay(). 

Changed in v6: 
- changed the inappropriate print message. 
- rebase to the latest code. 

Changed in v5: 
- add "*chan_dev = dma->chan_using->device->dev" for code cleanup. 
- add the test logs. 

Changed in v4: 
- cancelled "i2c_imx->use_dma". 
- changed "Dma" to "DMA". 
- add Timeout handling for Transfer complete. 

Changed in v3: 
- fix a bug when request the dma faild. 
- some minor fixes for coding style. 
- other minor fixes. 

Changed in v2: 
- remove has_dma_support property 
- unify i2c_imx_dma_rx and i2c_imx_dma_tx 
- unify i2c_imx_dma_read and i2c_imx_pio_read 
- unify i2c_imx_dma_write and i2c_imx_pio_write 

Added in v1: 
- Enable dma if it's support dma and transfer size bigger than the threshold. 
- Add device tree bindings for i2c eDMA support. 
- Add eDMA support for i2c driver. 


The test log for i2c DMA support: 

Starting kernel ... 

Booting Linux on physical CPU 0xf00 
Linux version 3.12.0+ (yuany@titan) (gcc version 4.8.3 20131202 (prerelease) (crosstool-NG linaro-1.13.1-4.8-2013.12 - Linaro GCC 2013.11) ) #34 SMP Sat Oct 11 17:15:15 CST 2014 
CPU: ARMv7 Processor [410fc075] revision 5 (ARMv7), cr=30c73c7d 
CPU: PIPT / VIPT nonaliasing data cache, VIPT aliasing instruction cache 
Machine: Freescale Layerscape LS1021A, model: LS1021A TWR Board 
Memory policy: ECC disabled, Data cache writealloc 
PERCPU: Embedded 7 pages/cpu @80e7a000 s7680 r8192 d12800 u32768 
Built 1 zonelists in Zone order, mobility grouping on. Total pages: 260096 
Kernel command line: root=/dev/ram rw console=ttyS0,115200 
PID hash table entries: 4096 (order: 2, 16384 bytes) 
Dentry cache hash table entries: 131072 (order: 7, 524288 bytes) 
Inode-cache hash table entries: 65536 (order: 6, 262144 bytes) 
Memory: 1014152K/1048576K available (4495K kernel code, 249K rwdata, 1352K rodata, 207K init, 224K bss, 34424K reserved, 0K highmem) 
Virtual kernel memory layout: 
vector : 0xffff0000 - 0xffff1000 ( 4 kB) 
fixmap : 0xfff00000 - 0xfffe0000 ( 896 kB) 
vmalloc : 0xc0800000 - 0xff000000 (1000 MB) 
lowmem : 0x80000000 - 0xc0000000 (1024 MB) 
pkmap : 0x7fe00000 - 0x80000000 ( 2 MB) 
modules : 0x7f000000 - 0x7fe00000 ( 14 MB) 
.text : 0x80008000 - 0x805bdf74 (5848 kB) 
.init : 0x805be000 - 0x805f1e00 ( 208 kB) 
.data : 0x805f2000 - 0x80630518 ( 250 kB) 
.bss : 0x80630520 - 0x80668628 ( 225 kB) 
SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=2, Nodes=1 
Hierarchical RCU implementation. 
RCU restricting CPUs from NR_CPUS=4 to nr_cpu_ids=2. 
NR_IRQS:16 nr_irqs:16 16 
Architected cp15 timer(s) running at 12.50MHz (phys). 
Switching to timer-based delay loop 
sched_clock: ARM arch timer >56 bits at 12500kHz, resolution 80ns 
sched_clock: 32 bits at 100 Hz, resolution 10000000ns, wraps every 4294967286ms 
Console: colour dummy device 80x30 
Calibrating delay loop (skipped), value calculated using timer frequency.. 25.00 BogoMIPS (lpj=125000) 
pid_max: default: 32768 minimum: 301 
Mount-cache hash table entries: 512 
CPU: Testing write buffer coherency: ok 
CPU0: update cpu_power 1024 
CPU0: thread -1, cpu 0, socket 15, mpidr 80000f00 
Setting up static identity map for 0x80469420 - 0x80469454 
CPU1: Booted secondary processor 
CPU1: update cpu_power 1024 
CPU1: thread -1, cpu 1, socket 15, mpidr 80000f01 
Brought up 2 CPUs 
SMP: Total of 2 processors activated. 
CPU: All CPU(s) started in HYP mode. 
CPU: Virtualization extensions available. 
devtmpfs: initialized 
VFP support v0.3: implementor 41 architecture 2 part 30 variant 7 rev 5 
NET: Registered protocol family 16 
DMA: preallocated 256 KiB pool for atomic coherent allocations 
cpuidle: using governor ladder 
cpuidle: using governor menu 
irq: no irq domain found for /soc/uqe@2400000/qeic@80 ! 
irq: no irq domain found for /soc/uqe@2400000/qeic@80 ! 
bio: create slab <bio-0> at 0 
layerscape-pcie 3400000.pcie: PCI host bridge to bus 0000:00 
pci_bus 0000:00: root bus resource [bus 00-ff] 
pci_bus 0000:00: root bus resource [io 0x4010000000-0x401000ffff] 
pci_bus 0000:00: root bus resource [mem 0x4100000000-0x41ffffffff] (bus address [0x00000000-0xffffffff]) 
PCI: bus0: Fast back to back transfers disabled 
PCI: bus1: Fast back to back transfers enabled 
pci 0000:00:00.0: BAR 0: assigned [mem 0x4100000000-0x4100ffffff 64bit] 
pci 0000:00:00.0: BAR 6: assigned [mem 0x4101000000-0x4101ffffff pref] 
pci 0000:00:00.0: PCI bridge to [bus 01] 
pci 0000:00:00.0: PCI bridge to [bus 01] 
layerscape-pcie 3500000.pcie: PCI host bridge to bus 0001:00 
pci_bus 0001:00: root bus resource [bus 00-ff] 
pci_bus 0001:00: root bus resource [io 0x4810000000-0x481000ffff] (bus address [0x480fff0000-0x480fffffff]) 
pci_bus 0001:00: root bus resource [mem 0x4900000000-0x49ffffffff] (bus address [0x00000000-0xffffffff]) 
PCI: bus0: Fast back to back transfers disabled 
PCI: bus1: Fast back to back transfers enabled 
pci 0001:00:00.0: BAR 0: assigned [mem 0x4900000000-0x4900ffffff 64bit] 
pci 0001:00:00.0: BAR 6: assigned [mem 0x4901000000-0x4901ffffff pref] 
pci 0001:00:00.0: PCI bridge to [bus 01] 
pci 0000:00:00.0: PCI bridge to [bus 01] 
pci 0001:00:00.0: PCI bridge to [bus 01] 
vgaarb: loaded 
SCSI subsystem initialized 
usbcore: registered new interface driver usbfs 
usbcore: registered new interface driver hub 
usbcore: registered new device driver usb 
i2c i2c-0: IMX I2C adapter registered 
of_dma_request_slave_channel: dma-names property of node '/soc/i2c@2180000' missing or empty 
i2c i2c-0: can't use DMA 
i2c i2c-1: IMX I2C adapter registered 
i2c i2c-1: using dma0chan16 (tx) and dma0chan17 (rx) for DMA transfers 
i2c i2c-2: IMX I2C adapter registered 
of_dma_request_slave_channel: dma-names property of node '/soc/i2c@21a0000' missing or empty 
i2c i2c-2: can't use DMA 
pps_core: LinuxPPS API ver. 1 registered 
pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <giometti@linux.it> 
PTP clock support registered 
fsl-ifc 1530000.ifc: Freescale Integrated Flash Controller 
Switched to clocksource arch_sys_counter 
NET: Registered protocol family 2 
TCP established hash table entries: 8192 (order: 4, 65536 bytes) 
TCP bind hash table entries: 8192 (order: 5, 163840 bytes) 
TCP: Hash tables configured (established 8192 bind 8192) 
TCP: reno registered 
UDP hash table entries: 512 (order: 2, 24576 bytes) 
UDP-Lite hash table entries: 512 (order: 2, 24576 bytes) 
NET: Registered protocol family 1 
RPC: Registered named UNIX socket transport module. 
RPC: Registered udp transport module. 
RPC: Registered tcp transport module. 
RPC: Registered tcp NFSv4.1 backchannel transport module. 
Trying to unpack rootfs image as initramfs... 
rootfs image is not initramfs (no cpio magic); looks like an initrd 
Freeing initrd memory: 18704K (bdce9000 - bef2d000) 
NFS: Registering the id_resolver key type 
Key type id_resolver registered 
Key type id_legacy registered 
jffs2: version 2.2. (NAND) © 2001-2006 Red Hat, Inc. 
msgmni has been set to 2017 
io scheduler noop registered 
io scheduler deadline registered 
io scheduler cfq registered (default) 
sii902x: probe of 1-0039 failed with error -1 
Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled 
21c0500.serial: ttyS0 at MMIO 0x21c0500 (irq = 118, base_baud = 9375000) is a Freescale 16550 FIFO64 
console [ttyS0] enabled 
21c0600.serial: ttyS1 at MMIO 0x21c0600 (irq = 118, base_baud = 9375000) is a Freescale 16550 FIFO64 
of_serial 2402000.ucc: clk or clock-frequency not defined 
of_serial: probe of 2402000.ucc failed with error -2 
of_serial 2402200.ucc: clk or clock-frequency not defined 
of_serial: probe of 2402200.ucc failed with error -2 
serial: Freescale lpuart driver 
2950000.serial: ttyLP0 at MMIO 0x2950000 (irq = 112, base_baud = 6250000) is a FSL_LPUART 
brd: module loaded 
loop: module loaded 
60000000.nor: Found 1 x16 devices at 0x0 in 16-bit bank. Manufacturer ID 0x000089 Chip ID 0x00227e 
Amd/Fujitsu Extended Query Table at 0x0040 
Amd/Fujitsu Extended Query version 1.3. 
number of CFI chips: 1 
4 ofpart partitions found on MTD device 60000000.nor 
Creating 4 MTD partitions on "60000000.nor": 
0x000000000000-0x000000020000 : "NOR RCW Image" 
0x000000020000-0x000000120000 : "NOR DTB Image" 
0x000000120000-0x000000920000 : "NOR Linux Kernel Image" 
0x000000920000-0x000003b20000 : "NOR Ramdisk Root File System" 
6Freescale DSPI master initialized 
CAN device driver interface 
flexcan 2a70000.can: device registered (reg_base=c081a000, irq=158) 
flexcan 2a80000.can: device registered (reg_base=c081c000, irq=159) 
libphy: Freescale PowerQUICC MII Bus: probed 
fsl-gianfar ethernet.4: enabled errata workarounds, flags: 0x4 
fsl-gianfar ethernet.4 eth0: mac: 00:04:9f:03:45:e8 
fsl-gianfar ethernet.4 eth0: Running with NAPI enabled 
fsl-gianfar ethernet.4 eth0: RX BD ring size for Q[0]: 256 
fsl-gianfar ethernet.4 eth0: TX BD ring size for Q[0]: 256 
fsl-gianfar ethernet.5: enabled errata workarounds, flags: 0x4 
fsl-gianfar ethernet.5 eth1: mac: 00:04:9f:03:45:e9 
fsl-gianfar ethernet.5 eth1: Running with NAPI enabled 
fsl-gianfar ethernet.5 eth1: RX BD ring size for Q[0]: 256 
fsl-gianfar ethernet.5 eth1: TX BD ring size for Q[0]: 256 
fsl-gianfar ethernet.6: enabled errata workarounds, flags: 0x4 
fsl-gianfar ethernet.6 eth2: mac: 00:04:9f:03:45:ea 
fsl-gianfar ethernet.6 eth2: Running with NAPI enabled 
fsl-gianfar ethernet.6 eth2: RX BD ring size for Q[0]: 256 
fsl-gianfar ethernet.6 eth2: TX BD ring size for Q[0]: 256 
pps pps0: new PPS source ptp0 
e1000: Intel(R) PRO/1000 Network Driver - version 7.3.21-k8-NAPI 
e1000: Copyright (c) 1999-2006 Intel Corporation. 
e1000e: Intel(R) PRO/1000 Network Driver - 2.3.2-k 
e1000e: Copyright(c) 1999 - 2013 Intel Corporation. 
xhci-hcd xhci-hcd.0.auto: xHCI Host Controller 
xhci-hcd xhci-hcd.0.auto: new USB bus registered, assigned bus number 1 
xhci-hcd xhci-hcd.0.auto: irq 125, io mem 0x03100000 
hub 1-0:1.0: USB hub found 
hub 1-0:1.0: 1 port detected 
xhci-hcd xhci-hcd.0.auto: xHCI Host Controller 
xhci-hcd xhci-hcd.0.auto: new USB bus registered, assigned bus number 2 
hub 2-0:1.0: USB hub found 
hub 2-0:1.0: 1 port detected 
usbcore: registered new interface driver usb-storage 
mousedev: PS/2 mouse device common for all mice 
i2c /dev entries driver 
sdhci: Secure Digital Host Controller Interface driver 
sdhci: Copyright(c) Pierre Ossman 
sdhci-pltfm: SDHCI platform and OF driver helper 
mmc0: SDHCI controller on 1560000.esdhc [1560000.esdhc] using ADMA 
Value in jrstart addr c0e0005c, value prev 0 new f 
caam 1700000.crypto: Instantiated RNG4 SH0 
mmc0: new SDHC card at address 8415 
caam 1700000.crypto: Instantiated RNG4 SH1 
caam 1700000.crypto: device ID = 0x0a140300 (Era 67108864) 
caam 1700000.crypto: job rings = 4, qi = 0 
mmcblk0: mmc0:8415 SD04G 3.69 GiB 
caam algorithms registered in /proc/crypto 
mmcblk0: 
caam_jr 1710000.jr: registering rng-caam 
usbcore: registered new interface driver usbhid 
usbhid: USB HID core driver 
TCP: cubic registered 
Initializing XFRM netlink socket 
NET: Registered protocol family 10 
sit: IPv6 over IPv4 tunneling driver 
NET: Registered protocol family 17 
NET: Registered protocol family 15 
can: controller area network core (rev 20120528 abi 9) 
NET: Registered protocol family 29 
can: raw protocol (rev 20120528) 
Key type dns_resolver registered 
drivers/rtc/hctosys.c: unable to open rtc device (rtc0) 
RAMDISK: gzip image found at block 0 
usb 1-1: new high-speed USB device number 2 using xhci-hcd 
hub 1-1:1.0: USB hub found 
hub 1-1:1.0: 4 ports detected 
usb 2-1: new SuperSpeed USB device number 2 using xhci-hcd 
usb 2-1: Parent hub missing LPM exit latency info. Power management will be impacted. 
hub 2-1:1.0: USB hub found 
hub 2-1:1.0: 4 ports detected 
VFS: Mounted root (ext2 filesystem) on device 1:0. 
devtmpfs: mounted 
Freeing unused kernel memory: 204K (805be000 - 805f1000) 
INIT: version 2.88 booting 
Starting udev 
udevd[114]: starting version 182 
FAT-fs (mmcblk0): Volume was not properly unmounted. Some data may be corrupt. Please run fsck. 
Starting Bootlog daemon: bootlogd. 
Populating dev cache 
Configuring network interfaces... IPv6: ADDRCONF(NETDEV_UP): eth0: link is not ready 
udhcpc (v1.21.1) started 
Sending discover... 
libphy: mdio@2d24000:02 - Link is Down 
Sending discover... 
libphy: mdio@2d24000:02 - Link is Up - 1000/Full 
IPv6: ADDRCONF(NETDEV_CHANGE): eth0: link becomes ready 
Sending discover... 
Sending select for 10.193.20.87... 
Lease of 10.193.20.87 obtained, lease time 14400 
/etc/udhcpc.d/50default: Adding DNS 10.192.130.201 
/etc/udhcpc.d/50default: Adding DNS 10.211.0.3 
/etc/udhcpc.d/50default: Adding DNS 10.196.51.200 
done. 
net.ipv4.conf.default.rp_filter = 1 
net.ipv4.conf.all.rp_filter = 1 
hwclock: can't open '/dev/misc/rtc': No such file or directory 
Wed Jun 25 11:59:00 UTC 2014 
hwclock: can't open '/dev/misc/rtc': No such file or directory 
Running postinst /etc/rpm-postinsts/100-sysvinit-inittab... 
Running postinst /etc/rpm-postinsts/101-debianutils... 
update-rc.d: /etc/init.d/run-postinsts exists during rc.d purge (continuing) 
Removing any system startup links for run-postinsts ... 
/etc/rcS.d/S99run-postinsts 
INIT: Entering runlevel: 5 
Starting OpenBSD Secure Shell server: sshd 
generating ssh RSA key... 
generating ssh ECDSA key... 
generating ssh DSA key... 
done. 
hwclock: can't open '/dev/misc/rtc': No such file or directory 
Starting network benchmark server: netserver. 
Starting system log daemon...0 
Starting kernel log daemon...0 
Starting internet superserver: xinetd. 
Stopping Bootlog daemon: bootlogd. 

Poky (Yocto Project Reference Distro) 1.5 ls1021atwr /dev/ttyS0 

ls1021atwr login: root 
root@ls1021atwr:~# i2cdump -y 1 0x52 i 
0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef 
00: 55 55 55 55 aa aa aa aa ff ff ff ff ff ff ff ff UUUU????........ 
10: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
20: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
30: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
40: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
50: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
60: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
70: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
90: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
a0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
b0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
c0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
d0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
e0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
root@ls1021atwr:~# i2cdump -y 1 0x52 
No size specified (using byte-data access) 
0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef 
00: 55 55 55 55 aa aa aa aa ff ff ff ff ff ff ff ff UUUU????........ 
10: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
20: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
30: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
40: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
50: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
60: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
70: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
90: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
a0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
b0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
c0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
d0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
e0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
root@ls1021atwr:~# i2cset -f -y 1 0x52 0x00 0xa0 0xa1 0xa2 0xa3 0xa4 0xa5 0xa6 0xa7 0xa8 0xa9 0xaa 0xab 0xac 0xad 0xae 0xaf i 
root@ls1021atwr:~# i2cset -f -y 1 0x52 0x10 0xb0 0xb1 0xb2 0xb3 0xb4 0xb5 0xb6 0xb7 0xb8 0xb9 0xba 0xbb 0xbc 0xbd 0xbe 0xbf i 
root@ls1021atwr:~# i2cset -f -y 1 0x52 0x20 0xc0 0xc1 0xc2 0xc3 0xc4 0xc5 0xc6 0xc7 0xc8 0xc9 0xca 0xcb 0xcc 0xcd 0xce 0xcf i 
root@ls1021atwr:~# i2cset -f -y 1 0x52 0x30 0xd0 0xd1 0xd2 0xd3 0xd4 0xd5 0xd6 0xd7 0xd8 0xd9 0xda 0xdb 0xdc 0xdd 0xde 0xdf i 
root@ls1021atwr:~# i2cset -f -y 1 0x52 0x40 0xe0 0xe1 0xe2 0xe3 0xe4 0xe5 0xe6 0xe7 0xe8 0xe9 0xea 0xeb 0xec 0xed 0xee 0xef i 
root@ls1021atwr:~# i2cdump -y 1 0x52 i 
0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef 
00: a0 a1 a2 a3 a4 a5 a6 a7 a8 a9 aa ab ac ad ae af ???????????????? 
10: b0 b1 b2 b3 b4 b5 b6 b7 b8 b9 ba bb bc bd be bf ???????????????? 
20: c0 c1 c2 c3 c4 c5 c6 c7 c8 c9 ca cb cc cd ce cf ???????????????? 
30: d0 d1 d2 d3 d4 d5 d6 d7 d8 d9 da db dc dd de df ???????????????? 
40: e0 e1 e2 e3 e4 e5 e6 e7 e8 e9 ea eb ec ed ee ef ???????????????? 
50: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
60: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
70: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
90: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
a0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
b0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
c0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
d0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
e0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
root@ls1021atwr:~# i2cdump -y 1 0x52 
No size specified (using byte-data access) 
0 1 2 3 4 5 6 7 8 9 a b c d e f 0123456789abcdef 
00: a0 a1 a2 a3 a4 a5 a6 a7 a8 a9 aa ab ac ad ae af ???????????????? 
10: b0 b1 b2 b3 b4 b5 b6 b7 b8 b9 ba bb bc bd be bf ???????????????? 
20: c0 c1 c2 c3 c4 c5 c6 c7 c8 c9 ca cb cc cd ce cf ???????????????? 
30: d0 d1 d2 d3 d4 d5 d6 d7 d8 d9 da db dc dd de df ???????????????? 
40: e0 e1 e2 e3 e4 e5 e6 e7 e8 e9 ea eb ec ed ee ef ???????????????? 
50: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
60: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
70: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
90: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
a0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
b0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
c0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
d0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
e0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
f0: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ................ 
root@ls1021atwr:~# 

_______________________________________________
linux-arm-kernel mailing list
linux-arm-kernel@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

[PATCH v9 1/3] i2c: imx: Sort include headers alphabetically

[Yuan Yao]

If the inlcude headers aren't sorted alphabetically, then the
logical choice is to append new ones, however that creates a
lot of potential for conflicts or duplicates because every change
will then add new includes in the same location.

Signed-off-by: Yuan Yao <yao.yuan@freescale.com>
---
 drivers/i2c/busses/i2c-imx.c | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index c48e46a..2452b57 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -37,22 +37,22 @@
 /** Includes *******************************************************************
 *******************************************************************************/
 
-#include <linux/init.h>
-#include <linux/kernel.h>
-#include <linux/module.h>
-#include <linux/errno.h>
-#include <linux/err.h>
-#include <linux/interrupt.h>
+#include <linux/clk.h>
 #include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/errno.h>
 #include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
 #include <linux/io.h>
-#include <linux/sched.h>
-#include <linux/platform_device.h>
-#include <linux/clk.h>
-#include <linux/slab.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
 #include <linux/platform_data/i2c-imx.h>
+#include <linux/platform_device.h>
+#include <linux/sched.h>
+#include <linux/slab.h>
 
 /** Defines ********************************************************************
 *******************************************************************************/
-- 
2.1.0.27.g96db324

[PATCH v9 2/3] Documentation:add DMA support for freescale i2c driver

[Yuan Yao]

Add i2c dts node properties for eDMA support, them depend on the eDMA driver.

Signed-off-by: Yuan Yao <yao.yuan-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
---
 Documentation/devicetree/bindings/i2c/i2c-imx.txt | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/Documentation/devicetree/bindings/i2c/i2c-imx.txt b/Documentation/devicetree/bindings/i2c/i2c-imx.txt
index 4a8513e..52d37fd 100644
--- a/Documentation/devicetree/bindings/i2c/i2c-imx.txt
+++ b/Documentation/devicetree/bindings/i2c/i2c-imx.txt
@@ -11,6 +11,8 @@ Required properties:
 Optional properties:
 - clock-frequency : Constains desired I2C/HS-I2C bus clock frequency in Hz.
   The absence of the propoerty indicates the default frequency 100 kHz.
+- dmas: A list of two dma specifiers, one for each entry in dma-names.
+- dma-names: should contain "tx" and "rx".
 
 Examples:
 
@@ -26,3 +28,12 @@ i2c@70038000 { /* HS-I2C on i.MX51 */
 	interrupts = <64>;
 	clock-frequency = <400000>;
 };
+
+i2c0: i2c@40066000 { /* i2c0 on vf610 */
+	compatible = "fsl,vf610-i2c";
+	reg = <0x40066000 0x1000>;
+	interrupts =<0 71 0x04>;
+	dmas = <&edma0 0 50>,
+		<&edma0 0 51>;
+	dma-names = "rx","tx";
+};
-- 
1.8.4

[PATCH v9 3/3] i2c: imx: add DMA support for freescale i2c driver

[Yuan Yao]

Add dma support for i2c. This function depend on DMA driver.
You can turn on it by write both the dmas and dma-name properties in dts node.
DMA is optional, even DMA request unsuccessfully, i2c can also work well.

Signed-off-by: Yuan Yao <yao.yuan@freescale.com>
---
 drivers/i2c/busses/i2c-imx.c | 327 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 325 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
index 2452b57..e58c771 100644
--- a/drivers/i2c/busses/i2c-imx.c
+++ b/drivers/i2c/busses/i2c-imx.c
@@ -38,7 +38,11 @@
 *******************************************************************************/
 
 #include <linux/clk.h>
+#include <linux/completion.h>
 #include <linux/delay.h>
+#include <linux/dma-mapping.h>
+#include <linux/dmaengine.h>
+#include <linux/dmapool.h>
 #include <linux/err.h>
 #include <linux/errno.h>
 #include <linux/i2c.h>
@@ -49,6 +53,7 @@
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/of_device.h>
+#include <linux/of_dma.h>
 #include <linux/platform_data/i2c-imx.h>
 #include <linux/platform_device.h>
 #include <linux/sched.h>
@@ -63,6 +68,13 @@
 /* Default value */
 #define IMX_I2C_BIT_RATE	100000	/* 100kHz */
 
+/*
+ * Enable DMA if transfer byte size is bigger than this threshold.
+ * As the hardware request, it must bigger than 4 bytes.
+ */
+#define IMX_I2C_DMA_THRESHOLD	16
+#define IMX_I2C_DMA_TIMEOUT	1000
+
 /* IMX I2C registers:
  * the I2C register offset is different between SoCs,
  * to provid support for all these chips, split the
@@ -88,6 +100,7 @@
 #define I2SR_IBB	0x20
 #define I2SR_IAAS	0x40
 #define I2SR_ICF	0x80
+#define I2CR_DMAEN	0x02
 #define I2CR_RSTA	0x04
 #define I2CR_TXAK	0x08
 #define I2CR_MTX	0x10
@@ -174,6 +187,17 @@ struct imx_i2c_hwdata {
 	unsigned		i2cr_ien_opcode;
 };
 
+struct imx_i2c_dma {
+	struct dma_chan		*chan_tx;
+	struct dma_chan		*chan_rx;
+	struct dma_chan		*chan_using;
+	struct completion	cmd_complete;
+	dma_addr_t		dma_buf;
+	unsigned int		dma_len;
+	unsigned int		dma_transfer_dir;
+	unsigned int		dma_data_dir;
+};
+
 struct imx_i2c_struct {
 	struct i2c_adapter	adapter;
 	struct clk		*clk;
@@ -186,6 +210,8 @@ struct imx_i2c_struct {
 	unsigned int		cur_clk;
 	unsigned int		bitrate;
 	const struct imx_i2c_hwdata	*hwdata;
+
+	struct imx_i2c_dma	*dma;
 };
 
 static const struct imx_i2c_hwdata imx1_i2c_hwdata  = {
@@ -256,6 +282,132 @@ static inline unsigned char imx_i2c_read_reg(struct imx_i2c_struct *i2c_imx,
 	return readb(i2c_imx->base + (reg << i2c_imx->hwdata->regshift));
 }
 
+/* Functions for DMA support */
+static int i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx,
+						dma_addr_t phy_addr)
+{
+	struct imx_i2c_dma *dma;
+	struct dma_slave_config dma_sconfig;
+	struct device *dev = &i2c_imx->adapter.dev;
+	int ret;
+
+	dma = devm_kzalloc(dev, sizeof(*dma), GFP_KERNEL);
+	if (!dma)
+		return -ENOMEM;
+
+	dma->chan_tx = dma_request_slave_channel(dev, "tx");
+	if (!dma->chan_tx) {
+		dev_dbg(dev, "can't request DMA tx channel\n");
+		ret = -ENODEV;
+		goto fail_al;
+	}
+
+	dma_sconfig.dst_addr = phy_addr +
+				(IMX_I2C_I2DR << i2c_imx->hwdata->regshift);
+	dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+	dma_sconfig.dst_maxburst = 1;
+	dma_sconfig.direction = DMA_MEM_TO_DEV;
+	ret = dmaengine_slave_config(dma->chan_tx, &dma_sconfig);
+	if (ret < 0) {
+		dev_dbg(dev, "can't configure tx channel\n");
+		goto fail_tx;
+	}
+
+	dma->chan_rx = dma_request_slave_channel(dev, "rx");
+	if (!dma->chan_rx) {
+		dev_dbg(dev, "can't request DMA rx channel\n");
+		ret = -ENODEV;
+		goto fail_tx;
+	}
+
+	dma_sconfig.src_addr = phy_addr +
+				(IMX_I2C_I2DR << i2c_imx->hwdata->regshift);
+	dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
+	dma_sconfig.src_maxburst = 1;
+	dma_sconfig.direction = DMA_DEV_TO_MEM;
+	ret = dmaengine_slave_config(dma->chan_rx, &dma_sconfig);
+	if (ret < 0) {
+		dev_dbg(dev, "can't configure rx channel\n");
+		goto fail_rx;
+	}
+
+	i2c_imx->dma = dma;
+	init_completion(&dma->cmd_complete);
+	dev_info(dev, "using %s (tx) and %s (rx) for DMA transfers\n",
+		dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx));
+
+	return 0;
+
+fail_rx:
+	dma_release_channel(dma->chan_rx);
+fail_tx:
+	dma_release_channel(dma->chan_tx);
+fail_al:
+	devm_kfree(dev, dma);
+	dev_info(dev, "can't use DMA\n");
+
+	return ret;
+}
+
+static void i2c_imx_dma_callback(void *arg)
+{
+	struct imx_i2c_struct *i2c_imx = (struct imx_i2c_struct *)arg;
+	struct imx_i2c_dma *dma = i2c_imx->dma;
+
+	dma_unmap_single(dma->chan_using->device->dev, dma->dma_buf,
+			dma->dma_len, dma->dma_data_dir);
+	complete(&dma->cmd_complete);
+}
+
+static int i2c_imx_dma_xfer(struct imx_i2c_struct *i2c_imx,
+					struct i2c_msg *msgs)
+{
+	struct imx_i2c_dma *dma = i2c_imx->dma;
+	struct dma_async_tx_descriptor *txdesc;
+	struct device *dev = &i2c_imx->adapter.dev;
+	struct device *chan_dev = dma->chan_using->device->dev;
+
+	dma->dma_buf = dma_map_single(chan_dev, msgs->buf,
+					dma->dma_len, dma->dma_data_dir);
+	if (dma_mapping_error(chan_dev, dma->dma_buf)) {
+		dev_err(dev, "DMA mapping failed\n");
+		return -EINVAL;
+	}
+
+	txdesc = dmaengine_prep_slave_single(dma->chan_using, dma->dma_buf,
+					dma->dma_len, dma->dma_transfer_dir,
+					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
+	if (!txdesc) {
+		dev_err(dev, "Not able to get desc for DMA xfer\n");
+		dma_unmap_single(chan_dev, dma->dma_buf,
+					dma->dma_len, dma->dma_data_dir);
+		return -EINVAL;
+	}
+
+	txdesc->callback = i2c_imx_dma_callback;
+	txdesc->callback_param = i2c_imx;
+	dmaengine_submit(txdesc);
+	dma_async_issue_pending(dma->chan_using);
+
+	return 0;
+}
+
+static void i2c_imx_dma_free(struct imx_i2c_struct *i2c_imx)
+{
+	struct imx_i2c_dma *dma = i2c_imx->dma;
+
+	dma->dma_buf = 0;
+	dma->dma_len = 0;
+
+	dma_release_channel(dma->chan_tx);
+	dma->chan_tx = NULL;
+
+	dma_release_channel(dma->chan_rx);
+	dma->chan_rx = NULL;
+
+	dma->chan_using = NULL;
+}
+
 /** Functions for IMX I2C adapter driver ***************************************
 *******************************************************************************/
 
@@ -387,6 +539,7 @@ static int i2c_imx_start(struct imx_i2c_struct *i2c_imx)
 	i2c_imx->stopped = 0;
 
 	temp |= I2CR_IIEN | I2CR_MTX | I2CR_TXAK;
+	temp &= ~I2CR_DMAEN;
 	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
 	return result;
 }
@@ -400,6 +553,8 @@ static void i2c_imx_stop(struct imx_i2c_struct *i2c_imx)
 		dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
 		temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
 		temp &= ~(I2CR_MSTA | I2CR_MTX);
+		if (i2c_imx->dma)
+			temp &= ~I2CR_DMAEN;
 		imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
 	}
 	if (is_imx1_i2c(i2c_imx)) {
@@ -440,6 +595,159 @@ static irqreturn_t i2c_imx_isr(int irq, void *dev_id)
 	return IRQ_NONE;
 }
 
+static int i2c_imx_dma_write(struct imx_i2c_struct *i2c_imx,
+					struct i2c_msg *msgs)
+{
+	int result;
+	unsigned int temp = 0;
+	unsigned long orig_jiffies = jiffies;
+	struct imx_i2c_dma *dma = i2c_imx->dma;
+	struct device *dev = &i2c_imx->adapter.dev;
+
+	dma->chan_using = dma->chan_tx;
+	dma->dma_transfer_dir = DMA_MEM_TO_DEV;
+	dma->dma_data_dir = DMA_TO_DEVICE;
+	dma->dma_len = msgs->len - 1;
+	result = i2c_imx_dma_xfer(i2c_imx, msgs);
+	if (result)
+		return result;
+
+	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+	temp |= I2CR_DMAEN;
+	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+
+	/*
+	 * Write slave address.
+	 * The first byte must be transmitted by the CPU.
+	 */
+	imx_i2c_write_reg(msgs->addr << 1, i2c_imx, IMX_I2C_I2DR);
+	reinit_completion(&i2c_imx->dma->cmd_complete);
+	result = wait_for_completion_interruptible_timeout(
+				&i2c_imx->dma->cmd_complete,
+				msecs_to_jiffies(IMX_I2C_DMA_TIMEOUT));
+	if (result <= 0) {
+		dmaengine_terminate_all(dma->chan_using);
+		return result ?: -ETIMEDOUT;
+	}
+
+	/* Waiting for transfer complete. */
+	while (1) {
+		temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
+		if (temp & I2SR_ICF)
+			break;
+		if (time_after(jiffies, orig_jiffies +
+				msecs_to_jiffies(IMX_I2C_DMA_TIMEOUT))) {
+			dev_dbg(dev, "<%s> Timeout\n", __func__);
+			return -ETIMEDOUT;
+		}
+		schedule();
+	}
+
+	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+	temp &= ~I2CR_DMAEN;
+	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+
+	/* The last data byte must be transferred by the CPU. */
+	imx_i2c_write_reg(msgs->buf[msgs->len-1],
+				i2c_imx, IMX_I2C_I2DR);
+	result = i2c_imx_trx_complete(i2c_imx);
+	if (result)
+		return result;
+
+	result = i2c_imx_acked(i2c_imx);
+	if (result)
+		return result;
+
+	return 0;
+}
+
+static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx,
+			struct i2c_msg *msgs, bool is_lastmsg)
+{
+	int result;
+	unsigned int temp;
+	unsigned long orig_jiffies;
+	struct imx_i2c_dma *dma = i2c_imx->dma;
+	struct device *dev = &i2c_imx->adapter.dev;
+
+	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+	temp |= I2CR_DMAEN;
+	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+
+	dma->chan_using = dma->chan_rx;
+	dma->dma_transfer_dir = DMA_DEV_TO_MEM;
+	dma->dma_data_dir = DMA_FROM_DEVICE;
+	/* The last two data bytes must be transferred by the CPU. */
+	dma->dma_len = msgs->len - 2;
+	result = i2c_imx_dma_xfer(i2c_imx, msgs);
+	if (result)
+		return result;
+
+	reinit_completion(&i2c_imx->dma->cmd_complete);
+	result = wait_for_completion_interruptible_timeout(
+				&i2c_imx->dma->cmd_complete,
+				msecs_to_jiffies(IMX_I2C_DMA_TIMEOUT));
+	if (result <= 0) {
+		dmaengine_terminate_all(dma->chan_using);
+		return result ?: -ETIMEDOUT;
+	}
+
+	/* waiting for transfer complete. */
+	while (1) {
+		temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
+		if (temp & I2SR_ICF)
+			break;
+		if (time_after(jiffies, orig_jiffies +
+				msecs_to_jiffies(IMX_I2C_DMA_TIMEOUT))) {
+			dev_dbg(dev, "<%s> Timeout\n", __func__);
+			return -ETIMEDOUT;
+		}
+		schedule();
+	}
+
+	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+	temp &= ~I2CR_DMAEN;
+	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+
+	/* read n-1 byte data */
+	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+	temp |= I2CR_TXAK;
+	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+
+	msgs->buf[msgs->len-2] = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
+	/* read n byte data */
+	result = i2c_imx_trx_complete(i2c_imx);
+	if (result)
+		return result;
+
+	if (is_lastmsg) {
+		/*
+		 * It must generate STOP before read I2DR to prevent
+		 * controller from generating another clock cycle
+		 */
+		dev_dbg(dev, "<%s> clear MSTA\n", __func__);
+		temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
+		temp &= ~(I2CR_MSTA | I2CR_MTX);
+		imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
+		i2c_imx_bus_busy(i2c_imx, 0);
+		i2c_imx->stopped = 1;
+	} else {
+		/*
+		 * For i2c master receiver repeat restart operation like:
+		 * read -> repeat MSTA -> read/write
+		 * The controller must set MTX before read the last byte in
+		 * the first read operation, otherwise the first read cost
+		 * one extra clock cycle.
+		 */
+		temp = readb(i2c_imx->base + IMX_I2C_I2CR);
+		temp |= I2CR_MTX;
+		writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
+	}
+	msgs->buf[msgs->len-1] = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
+
+	return 0;
+}
+
 static int i2c_imx_write(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs)
 {
 	int i, result;
@@ -509,6 +817,9 @@ static int i2c_imx_read(struct imx_i2c_struct *i2c_imx, struct i2c_msg *msgs, bo
 
 	dev_dbg(&i2c_imx->adapter.dev, "<%s> read data\n", __func__);
 
+	if (i2c_imx->dma && msgs->len >= IMX_I2C_DMA_THRESHOLD && !block_data)
+		return i2c_imx_dma_read(i2c_imx, msgs, is_lastmsg);
+
 	/* read data */
 	for (i = 0; i < msgs->len; i++) {
 		u8 len = 0;
@@ -623,8 +934,12 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
 #endif
 		if (msgs[i].flags & I2C_M_RD)
 			result = i2c_imx_read(i2c_imx, &msgs[i], is_lastmsg);
-		else
-			result = i2c_imx_write(i2c_imx, &msgs[i]);
+		else {
+			if (i2c_imx->dma && msgs[i].len >= IMX_I2C_DMA_THRESHOLD)
+				result = i2c_imx_dma_write(i2c_imx, &msgs[i]);
+			else
+				result = i2c_imx_write(i2c_imx, &msgs[i]);
+		}
 		if (result)
 			goto fail0;
 	}
@@ -659,6 +974,7 @@ static int i2c_imx_probe(struct platform_device *pdev)
 	struct imxi2c_platform_data *pdata = dev_get_platdata(&pdev->dev);
 	void __iomem *base;
 	int irq, ret;
+	dma_addr_t phy_addr;
 
 	dev_dbg(&pdev->dev, "<%s>\n", __func__);
 
@@ -673,6 +989,7 @@ static int i2c_imx_probe(struct platform_device *pdev)
 	if (IS_ERR(base))
 		return PTR_ERR(base);
 
+	phy_addr = (dma_addr_t)res->start;
 	i2c_imx = devm_kzalloc(&pdev->dev, sizeof(struct imx_i2c_struct),
 				GFP_KERNEL);
 	if (!i2c_imx)
@@ -748,6 +1065,9 @@ static int i2c_imx_probe(struct platform_device *pdev)
 		i2c_imx->adapter.name);
 	dev_info(&i2c_imx->adapter.dev, "IMX I2C adapter registered\n");
 
+	/* Init DMA config if support*/
+	i2c_imx_dma_request(i2c_imx, phy_addr);
+
 	return 0;   /* Return OK */
 
 clk_disable:
@@ -763,6 +1083,9 @@ static int i2c_imx_remove(struct platform_device *pdev)
 	dev_dbg(&i2c_imx->adapter.dev, "adapter removed\n");
 	i2c_del_adapter(&i2c_imx->adapter);
 
+	if (i2c_imx->dma)
+		i2c_imx_dma_free(i2c_imx);
+
 	/* setup chip registers to defaults */
 	imx_i2c_write_reg(0, i2c_imx, IMX_I2C_IADR);
 	imx_i2c_write_reg(0, i2c_imx, IMX_I2C_IFDR);
-- 
2.1.0.27.g96db324

RE: [PATCH v9 3/3] i2c: imx: add DMA support for freescale i2c driver

[Yao Yuan]

Hi Wolfram,

I have fixed the issues in v9. Could you please help to review this patch?

Thanks & Regards
Yuan Yao

> -----Original Message-----
> From: linux-arm-kernel [mailto:linux-arm-kernel-
> bounces@lists.infradead.org] On Behalf Of Yuan Yao
> Sent: Saturday, October 11, 2014 6:57 PM
> To: wsa@the-dreams.de; marex@denx.de
> Cc: mark.rutland@arm.com; linux-kernel@vger.kernel.org; linux-
> i2c@vger.kernel.org; Duan Fugang-B38611; shawn.guo@linaro.org; linux-arm-
> kernel@lists.infradead.org; LW@KARO-electronics.de
> Subject: [PATCH v9 3/3] i2c: imx: add DMA support for freescale i2c
> driver
> 
> Add dma support for i2c. This function depend on DMA driver.
> You can turn on it by write both the dmas and dma-name properties in dts
> node.
> DMA is optional, even DMA request unsuccessfully, i2c can also work well.
> 
> Signed-off-by: Yuan Yao <yao.yuan@freescale.com>
> ---
>  drivers/i2c/busses/i2c-imx.c | 327
> ++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 325 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/i2c/busses/i2c-imx.c b/drivers/i2c/busses/i2c-imx.c
> index 2452b57..e58c771 100644
> --- a/drivers/i2c/busses/i2c-imx.c
> +++ b/drivers/i2c/busses/i2c-imx.c
> @@ -38,7 +38,11 @@
> 
> *************************************************************************
> ******/
> 
>  #include <linux/clk.h>
> +#include <linux/completion.h>
>  #include <linux/delay.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/dmaengine.h>
> +#include <linux/dmapool.h>
>  #include <linux/err.h>
>  #include <linux/errno.h>
>  #include <linux/i2c.h>
> @@ -49,6 +53,7 @@
>  #include <linux/module.h>
>  #include <linux/of.h>
>  #include <linux/of_device.h>
> +#include <linux/of_dma.h>
>  #include <linux/platform_data/i2c-imx.h>  #include
> <linux/platform_device.h>  #include <linux/sched.h> @@ -63,6 +68,13 @@
>  /* Default value */
>  #define IMX_I2C_BIT_RATE	100000	/* 100kHz */
> 
> +/*
> + * Enable DMA if transfer byte size is bigger than this threshold.
> + * As the hardware request, it must bigger than 4 bytes.
> + */
> +#define IMX_I2C_DMA_THRESHOLD	16
> +#define IMX_I2C_DMA_TIMEOUT	1000
> +
>  /* IMX I2C registers:
>   * the I2C register offset is different between SoCs,
>   * to provid support for all these chips, split the @@ -88,6 +100,7 @@
>  #define I2SR_IBB	0x20
>  #define I2SR_IAAS	0x40
>  #define I2SR_ICF	0x80
> +#define I2CR_DMAEN	0x02
>  #define I2CR_RSTA	0x04
>  #define I2CR_TXAK	0x08
>  #define I2CR_MTX	0x10
> @@ -174,6 +187,17 @@ struct imx_i2c_hwdata {
>  	unsigned		i2cr_ien_opcode;
>  };
> 
> +struct imx_i2c_dma {
> +	struct dma_chan		*chan_tx;
> +	struct dma_chan		*chan_rx;
> +	struct dma_chan		*chan_using;
> +	struct completion	cmd_complete;
> +	dma_addr_t		dma_buf;
> +	unsigned int		dma_len;
> +	unsigned int		dma_transfer_dir;
> +	unsigned int		dma_data_dir;
> +};
> +
>  struct imx_i2c_struct {
>  	struct i2c_adapter	adapter;
>  	struct clk		*clk;
> @@ -186,6 +210,8 @@ struct imx_i2c_struct {
>  	unsigned int		cur_clk;
>  	unsigned int		bitrate;
>  	const struct imx_i2c_hwdata	*hwdata;
> +
> +	struct imx_i2c_dma	*dma;
>  };
> 
>  static const struct imx_i2c_hwdata imx1_i2c_hwdata  = { @@ -256,6
> +282,132 @@ static inline unsigned char imx_i2c_read_reg(struct
> imx_i2c_struct *i2c_imx,
>  	return readb(i2c_imx->base + (reg << i2c_imx->hwdata->regshift));  }
> 
> +/* Functions for DMA support */
> +static int i2c_imx_dma_request(struct imx_i2c_struct *i2c_imx,
> +						dma_addr_t phy_addr)
> +{
> +	struct imx_i2c_dma *dma;
> +	struct dma_slave_config dma_sconfig;
> +	struct device *dev = &i2c_imx->adapter.dev;
> +	int ret;
> +
> +	dma = devm_kzalloc(dev, sizeof(*dma), GFP_KERNEL);
> +	if (!dma)
> +		return -ENOMEM;
> +
> +	dma->chan_tx = dma_request_slave_channel(dev, "tx");
> +	if (!dma->chan_tx) {
> +		dev_dbg(dev, "can't request DMA tx channel\n");
> +		ret = -ENODEV;
> +		goto fail_al;
> +	}
> +
> +	dma_sconfig.dst_addr = phy_addr +
> +				(IMX_I2C_I2DR << i2c_imx->hwdata->regshift);
> +	dma_sconfig.dst_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
> +	dma_sconfig.dst_maxburst = 1;
> +	dma_sconfig.direction = DMA_MEM_TO_DEV;
> +	ret = dmaengine_slave_config(dma->chan_tx, &dma_sconfig);
> +	if (ret < 0) {
> +		dev_dbg(dev, "can't configure tx channel\n");
> +		goto fail_tx;
> +	}
> +
> +	dma->chan_rx = dma_request_slave_channel(dev, "rx");
> +	if (!dma->chan_rx) {
> +		dev_dbg(dev, "can't request DMA rx channel\n");
> +		ret = -ENODEV;
> +		goto fail_tx;
> +	}
> +
> +	dma_sconfig.src_addr = phy_addr +
> +				(IMX_I2C_I2DR << i2c_imx->hwdata->regshift);
> +	dma_sconfig.src_addr_width = DMA_SLAVE_BUSWIDTH_1_BYTE;
> +	dma_sconfig.src_maxburst = 1;
> +	dma_sconfig.direction = DMA_DEV_TO_MEM;
> +	ret = dmaengine_slave_config(dma->chan_rx, &dma_sconfig);
> +	if (ret < 0) {
> +		dev_dbg(dev, "can't configure rx channel\n");
> +		goto fail_rx;
> +	}
> +
> +	i2c_imx->dma = dma;
> +	init_completion(&dma->cmd_complete);
> +	dev_info(dev, "using %s (tx) and %s (rx) for DMA transfers\n",
> +		dma_chan_name(dma->chan_tx), dma_chan_name(dma->chan_rx));
> +
> +	return 0;
> +
> +fail_rx:
> +	dma_release_channel(dma->chan_rx);
> +fail_tx:
> +	dma_release_channel(dma->chan_tx);
> +fail_al:
> +	devm_kfree(dev, dma);
> +	dev_info(dev, "can't use DMA\n");
> +
> +	return ret;
> +}
> +
> +static void i2c_imx_dma_callback(void *arg) {
> +	struct imx_i2c_struct *i2c_imx = (struct imx_i2c_struct *)arg;
> +	struct imx_i2c_dma *dma = i2c_imx->dma;
> +
> +	dma_unmap_single(dma->chan_using->device->dev, dma->dma_buf,
> +			dma->dma_len, dma->dma_data_dir);
> +	complete(&dma->cmd_complete);
> +}
> +
> +static int i2c_imx_dma_xfer(struct imx_i2c_struct *i2c_imx,
> +					struct i2c_msg *msgs)
> +{
> +	struct imx_i2c_dma *dma = i2c_imx->dma;
> +	struct dma_async_tx_descriptor *txdesc;
> +	struct device *dev = &i2c_imx->adapter.dev;
> +	struct device *chan_dev = dma->chan_using->device->dev;
> +
> +	dma->dma_buf = dma_map_single(chan_dev, msgs->buf,
> +					dma->dma_len, dma->dma_data_dir);
> +	if (dma_mapping_error(chan_dev, dma->dma_buf)) {
> +		dev_err(dev, "DMA mapping failed\n");
> +		return -EINVAL;
> +	}
> +
> +	txdesc = dmaengine_prep_slave_single(dma->chan_using, dma->dma_buf,
> +					dma->dma_len, dma->dma_transfer_dir,
> +					DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
> +	if (!txdesc) {
> +		dev_err(dev, "Not able to get desc for DMA xfer\n");
> +		dma_unmap_single(chan_dev, dma->dma_buf,
> +					dma->dma_len, dma->dma_data_dir);
> +		return -EINVAL;
> +	}
> +
> +	txdesc->callback = i2c_imx_dma_callback;
> +	txdesc->callback_param = i2c_imx;
> +	dmaengine_submit(txdesc);
> +	dma_async_issue_pending(dma->chan_using);
> +
> +	return 0;
> +}
> +
> +static void i2c_imx_dma_free(struct imx_i2c_struct *i2c_imx) {
> +	struct imx_i2c_dma *dma = i2c_imx->dma;
> +
> +	dma->dma_buf = 0;
> +	dma->dma_len = 0;
> +
> +	dma_release_channel(dma->chan_tx);
> +	dma->chan_tx = NULL;
> +
> +	dma_release_channel(dma->chan_rx);
> +	dma->chan_rx = NULL;
> +
> +	dma->chan_using = NULL;
> +}
> +
>  /** Functions for IMX I2C adapter driver
> ***************************************
> 
> *************************************************************************
> ******/
> 
> @@ -387,6 +539,7 @@ static int i2c_imx_start(struct imx_i2c_struct
> *i2c_imx)
>  	i2c_imx->stopped = 0;
> 
>  	temp |= I2CR_IIEN | I2CR_MTX | I2CR_TXAK;
> +	temp &= ~I2CR_DMAEN;
>  	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
>  	return result;
>  }
> @@ -400,6 +553,8 @@ static void i2c_imx_stop(struct imx_i2c_struct
> *i2c_imx)
>  		dev_dbg(&i2c_imx->adapter.dev, "<%s>\n", __func__);
>  		temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
>  		temp &= ~(I2CR_MSTA | I2CR_MTX);
> +		if (i2c_imx->dma)
> +			temp &= ~I2CR_DMAEN;
>  		imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
>  	}
>  	if (is_imx1_i2c(i2c_imx)) {
> @@ -440,6 +595,159 @@ static irqreturn_t i2c_imx_isr(int irq, void
> *dev_id)
>  	return IRQ_NONE;
>  }
> 
> +static int i2c_imx_dma_write(struct imx_i2c_struct *i2c_imx,
> +					struct i2c_msg *msgs)
> +{
> +	int result;
> +	unsigned int temp = 0;
> +	unsigned long orig_jiffies = jiffies;
> +	struct imx_i2c_dma *dma = i2c_imx->dma;
> +	struct device *dev = &i2c_imx->adapter.dev;
> +
> +	dma->chan_using = dma->chan_tx;
> +	dma->dma_transfer_dir = DMA_MEM_TO_DEV;
> +	dma->dma_data_dir = DMA_TO_DEVICE;
> +	dma->dma_len = msgs->len - 1;
> +	result = i2c_imx_dma_xfer(i2c_imx, msgs);
> +	if (result)
> +		return result;
> +
> +	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
> +	temp |= I2CR_DMAEN;
> +	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
> +
> +	/*
> +	 * Write slave address.
> +	 * The first byte must be transmitted by the CPU.
> +	 */
> +	imx_i2c_write_reg(msgs->addr << 1, i2c_imx, IMX_I2C_I2DR);
> +	reinit_completion(&i2c_imx->dma->cmd_complete);
> +	result = wait_for_completion_interruptible_timeout(
> +				&i2c_imx->dma->cmd_complete,
> +				msecs_to_jiffies(IMX_I2C_DMA_TIMEOUT));
> +	if (result <= 0) {
> +		dmaengine_terminate_all(dma->chan_using);
> +		return result ?: -ETIMEDOUT;
> +	}
> +
> +	/* Waiting for transfer complete. */
> +	while (1) {
> +		temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
> +		if (temp & I2SR_ICF)
> +			break;
> +		if (time_after(jiffies, orig_jiffies +
> +				msecs_to_jiffies(IMX_I2C_DMA_TIMEOUT))) {
> +			dev_dbg(dev, "<%s> Timeout\n", __func__);
> +			return -ETIMEDOUT;
> +		}
> +		schedule();
> +	}
> +
> +	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
> +	temp &= ~I2CR_DMAEN;
> +	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
> +
> +	/* The last data byte must be transferred by the CPU. */
> +	imx_i2c_write_reg(msgs->buf[msgs->len-1],
> +				i2c_imx, IMX_I2C_I2DR);
> +	result = i2c_imx_trx_complete(i2c_imx);
> +	if (result)
> +		return result;
> +
> +	result = i2c_imx_acked(i2c_imx);
> +	if (result)
> +		return result;
> +
> +	return 0;
> +}
> +
> +static int i2c_imx_dma_read(struct imx_i2c_struct *i2c_imx,
> +			struct i2c_msg *msgs, bool is_lastmsg) {
> +	int result;
> +	unsigned int temp;
> +	unsigned long orig_jiffies;
> +	struct imx_i2c_dma *dma = i2c_imx->dma;
> +	struct device *dev = &i2c_imx->adapter.dev;
> +
> +	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
> +	temp |= I2CR_DMAEN;
> +	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
> +
> +	dma->chan_using = dma->chan_rx;
> +	dma->dma_transfer_dir = DMA_DEV_TO_MEM;
> +	dma->dma_data_dir = DMA_FROM_DEVICE;
> +	/* The last two data bytes must be transferred by the CPU. */
> +	dma->dma_len = msgs->len - 2;
> +	result = i2c_imx_dma_xfer(i2c_imx, msgs);
> +	if (result)
> +		return result;
> +
> +	reinit_completion(&i2c_imx->dma->cmd_complete);
> +	result = wait_for_completion_interruptible_timeout(
> +				&i2c_imx->dma->cmd_complete,
> +				msecs_to_jiffies(IMX_I2C_DMA_TIMEOUT));
> +	if (result <= 0) {
> +		dmaengine_terminate_all(dma->chan_using);
> +		return result ?: -ETIMEDOUT;
> +	}
> +
> +	/* waiting for transfer complete. */
> +	while (1) {
> +		temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2SR);
> +		if (temp & I2SR_ICF)
> +			break;
> +		if (time_after(jiffies, orig_jiffies +
> +				msecs_to_jiffies(IMX_I2C_DMA_TIMEOUT))) {
> +			dev_dbg(dev, "<%s> Timeout\n", __func__);
> +			return -ETIMEDOUT;
> +		}
> +		schedule();
> +	}
> +
> +	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
> +	temp &= ~I2CR_DMAEN;
> +	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
> +
> +	/* read n-1 byte data */
> +	temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
> +	temp |= I2CR_TXAK;
> +	imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
> +
> +	msgs->buf[msgs->len-2] = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
> +	/* read n byte data */
> +	result = i2c_imx_trx_complete(i2c_imx);
> +	if (result)
> +		return result;
> +
> +	if (is_lastmsg) {
> +		/*
> +		 * It must generate STOP before read I2DR to prevent
> +		 * controller from generating another clock cycle
> +		 */
> +		dev_dbg(dev, "<%s> clear MSTA\n", __func__);
> +		temp = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2CR);
> +		temp &= ~(I2CR_MSTA | I2CR_MTX);
> +		imx_i2c_write_reg(temp, i2c_imx, IMX_I2C_I2CR);
> +		i2c_imx_bus_busy(i2c_imx, 0);
> +		i2c_imx->stopped = 1;
> +	} else {
> +		/*
> +		 * For i2c master receiver repeat restart operation like:
> +		 * read -> repeat MSTA -> read/write
> +		 * The controller must set MTX before read the last byte in
> +		 * the first read operation, otherwise the first read cost
> +		 * one extra clock cycle.
> +		 */
> +		temp = readb(i2c_imx->base + IMX_I2C_I2CR);
> +		temp |= I2CR_MTX;
> +		writeb(temp, i2c_imx->base + IMX_I2C_I2CR);
> +	}
> +	msgs->buf[msgs->len-1] = imx_i2c_read_reg(i2c_imx, IMX_I2C_I2DR);
> +
> +	return 0;
> +}
> +
>  static int i2c_imx_write(struct imx_i2c_struct *i2c_imx, struct i2c_msg
> *msgs)  {
>  	int i, result;
> @@ -509,6 +817,9 @@ static int i2c_imx_read(struct imx_i2c_struct
> *i2c_imx, struct i2c_msg *msgs, bo
> 
>  	dev_dbg(&i2c_imx->adapter.dev, "<%s> read data\n", __func__);
> 
> +	if (i2c_imx->dma && msgs->len >= IMX_I2C_DMA_THRESHOLD
> && !block_data)
> +		return i2c_imx_dma_read(i2c_imx, msgs, is_lastmsg);
> +
>  	/* read data */
>  	for (i = 0; i < msgs->len; i++) {
>  		u8 len = 0;
> @@ -623,8 +934,12 @@ static int i2c_imx_xfer(struct i2c_adapter *adapter,
> #endif
>  		if (msgs[i].flags & I2C_M_RD)
>  			result = i2c_imx_read(i2c_imx, &msgs[i], is_lastmsg);
> -		else
> -			result = i2c_imx_write(i2c_imx, &msgs[i]);
> +		else {
> +			if (i2c_imx->dma && msgs[i].len >=
> IMX_I2C_DMA_THRESHOLD)
> +				result = i2c_imx_dma_write(i2c_imx, &msgs[i]);
> +			else
> +				result = i2c_imx_write(i2c_imx, &msgs[i]);
> +		}
>  		if (result)
>  			goto fail0;
>  	}
> @@ -659,6 +974,7 @@ static int i2c_imx_probe(struct platform_device *pdev)
>  	struct imxi2c_platform_data *pdata = dev_get_platdata(&pdev->dev);
>  	void __iomem *base;
>  	int irq, ret;
> +	dma_addr_t phy_addr;
> 
>  	dev_dbg(&pdev->dev, "<%s>\n", __func__);
> 
> @@ -673,6 +989,7 @@ static int i2c_imx_probe(struct platform_device *pdev)
>  	if (IS_ERR(base))
>  		return PTR_ERR(base);
> 
> +	phy_addr = (dma_addr_t)res->start;
>  	i2c_imx = devm_kzalloc(&pdev->dev, sizeof(struct imx_i2c_struct),
>  				GFP_KERNEL);
>  	if (!i2c_imx)
> @@ -748,6 +1065,9 @@ static int i2c_imx_probe(struct platform_device
> *pdev)
>  		i2c_imx->adapter.name);
>  	dev_info(&i2c_imx->adapter.dev, "IMX I2C adapter registered\n");
> 
> +	/* Init DMA config if support*/
> +	i2c_imx_dma_request(i2c_imx, phy_addr);
> +
>  	return 0;   /* Return OK */
> 
>  clk_disable:
> @@ -763,6 +1083,9 @@ static int i2c_imx_remove(struct platform_device
> *pdev)
>  	dev_dbg(&i2c_imx->adapter.dev, "adapter removed\n");
>  	i2c_del_adapter(&i2c_imx->adapter);
> 
> +	if (i2c_imx->dma)
> +		i2c_imx_dma_free(i2c_imx);
> +
>  	/* setup chip registers to defaults */
>  	imx_i2c_write_reg(0, i2c_imx, IMX_I2C_IADR);
>  	imx_i2c_write_reg(0, i2c_imx, IMX_I2C_IFDR);
> --
> 2.1.0.27.g96db324
> 
> 
> _______________________________________________
> linux-arm-kernel mailing list
> linux-arm-kernel@lists.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-arm-kernel

Re: [PATCH v9 3/3] i2c: imx: add DMA support for freescale i2c driver

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 1158 bytes --]

Hi,

mostly looking good...

> +#define IMX_I2C_DMA_THRESHOLD	16

Have you guessed or measured this value? A comment about this value
would be nice.

>  
> +struct imx_i2c_dma {
> +	struct dma_chan		*chan_tx;
> +	struct dma_chan		*chan_rx;
> +	struct dma_chan		*chan_using;
> +	struct completion	cmd_complete;
> +	dma_addr_t		dma_buf;
> +	unsigned int		dma_len;
> +	unsigned int		dma_transfer_dir;
> +	unsigned int		dma_data_dir;

Please use proper types as there are things like 'enum
dma_data_direction' and the likes...

> +	dmaengine_submit(txdesc);

This can fail, too. Use dma_submit_error() to check.

> +	result = wait_for_completion_interruptible_timeout(
> +				&i2c_imx->dma->cmd_complete,
> +				msecs_to_jiffies(IMX_I2C_DMA_TIMEOUT));

Have you tested signals extensively? I can't really recommend the
_intrruptible_ here. I don't see any cleaning up to get the bus to a
consistent state again. Most people drop the interruptible sooner or
later.

> +	/* Init DMA config if support*/
> +	i2c_imx_dma_request(i2c_imx, phy_addr);

Make this function void? DMA is optional anyhow.

Thanks,

   Wolfram


[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 819 bytes --]

RE: [PATCH v9 3/3] i2c: imx: add DMA support for freescale i2c driver

[Yao Yuan]

Thanks for your review.
Your suggestions is really helpful.

I will correct them in v10.

Best Regards,
Yuan Yao

> -----Original Message-----
> From: Wolfram Sang [mailto:wsa-z923LK4zBo2bacvFa/9K2g@public.gmane.org]
> Sent: Sunday, November 09, 2014 1:35 AM
> To: Yuan Yao-B46683
> Cc: marex-ynQEQJNshbs@public.gmane.org; LW-bxm8fMRDkQLDiMYJYoSAnRvVK+yQ3ZXh@public.gmane.org; mark.rutland-5wv7dgnIgG8@public.gmane.org; Duan
> Fugang-B38611; shawn.guo-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org; linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; linux-
> arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org; linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> Subject: Re: [PATCH v9 3/3] i2c: imx: add DMA support for freescale i2c
> driver
> 
> Hi,
> 
> mostly looking good...
> 
> > +#define IMX_I2C_DMA_THRESHOLD	16
> 
> Have you guessed or measured this value? A comment about this value would
> be nice.
> 
> >
> > +struct imx_i2c_dma {
> > +	struct dma_chan		*chan_tx;
> > +	struct dma_chan		*chan_rx;
> > +	struct dma_chan		*chan_using;
> > +	struct completion	cmd_complete;
> > +	dma_addr_t		dma_buf;
> > +	unsigned int		dma_len;
> > +	unsigned int		dma_transfer_dir;
> > +	unsigned int		dma_data_dir;
> 
> Please use proper types as there are things like 'enum
> dma_data_direction' and the likes...
> 
> > +	dmaengine_submit(txdesc);
> 
> This can fail, too. Use dma_submit_error() to check.
> 
> > +	result = wait_for_completion_interruptible_timeout(
> > +				&i2c_imx->dma->cmd_complete,
> > +				msecs_to_jiffies(IMX_I2C_DMA_TIMEOUT));
> 
> Have you tested signals extensively? I can't really recommend the
> _intrruptible_ here. I don't see any cleaning up to get the bus to a
> consistent state again. Most people drop the interruptible sooner or
> later.
> 
> > +	/* Init DMA config if support*/
> > +	i2c_imx_dma_request(i2c_imx, phy_addr);
> 
> Make this function void? DMA is optional anyhow.
> 
> Thanks,
> 
>    Wolfram