Linear workflow in Photoshop

First step is downloading/installing : OpenEXR for Photoshop
http://www.openexr.com/downloads.html

Be aware while Photoshop can import/export 32bit EXR files you will have many Photoshop options disabled.

• Brighness / Contrast : Disabled
• Levels: Enabled
• Curves: Disabled
• Exposure : Enabled