pcmcia: Implement CLKRUN protocol disabling for Ricoh bridges

Currently, "disable_clkrun" yenta_socket module parameter is only
implemented for TI CardBus bridges.
Add also an implementation for Ricoh bridges that have the necessary
setting documented in publicly available datasheets.

Tested on a RL5C476II with a Sunrich C-160 CardBus NIC that doesn't work
correctly unless the CLKRUN protocol is disabled.

Let's also make it clear in its description that the "disable_clkrun"
module parameter only works on these two previously mentioned brands of
CardBus bridges.

Signed-off-by: Maciej S. Szmigiero <[e-mail]>
Cc: [e-mail]
Signed-off-by: Dominik Brodowski <[e-mail]>

drivers/pcmcia/ricoh.h

···
 #define  RL5C4XX_MISC_CONTROL           0x2F /* 8 bit */
 #define  RL5C4XX_ZV_ENABLE              0x08
 
+/* Misc Control 3 Register */
+#define RL5C4XX_MISC3			0x00A2 /* 16 bit */
+#define  RL5C47X_MISC3_CB_CLKRUN_DIS	BIT(1)
+
 #ifdef __YENTA_H
 
 #define rl_misc(socket)		((socket)->private[0])
···
         }
 }
 
+static void ricoh_set_clkrun(struct yenta_socket *socket, bool quiet)
+{
+	u16 misc3;
+
+	/*
+	 * RL5C475II likely has this setting, too, however no datasheet
+	 * is publicly available for this chip
+	 */
+	if (socket->dev->device != PCI_DEVICE_ID_RICOH_RL5C476 &&
+	    socket->dev->device != PCI_DEVICE_ID_RICOH_RL5C478)
+		return;
+
+	if (socket->dev->revision < 0x80)
+		return;
+
+	misc3 = config_readw(socket, RL5C4XX_MISC3);
+	if (misc3 & RL5C47X_MISC3_CB_CLKRUN_DIS) {
+		if (!quiet)
+			dev_dbg(&socket->dev->dev,
+				"CLKRUN feature already disabled\n");
+	} else if (disable_clkrun) {
+		if (!quiet)
+			dev_info(&socket->dev->dev,
+				 "Disabling CLKRUN feature\n");
+		misc3 |= RL5C47X_MISC3_CB_CLKRUN_DIS;
+		config_writew(socket, RL5C4XX_MISC3, misc3);
+	}
+}
+
 static void ricoh_save_state(struct yenta_socket *socket)
 {
 	rl_misc(socket) = config_readw(socket, RL5C4XX_MISC);
···
 	config_writew(socket, RL5C4XX_16BIT_IO_0, rl_io(socket));
 	config_writew(socket, RL5C4XX_16BIT_MEM_0, rl_mem(socket));
 	config_writew(socket, RL5C4XX_CONFIG, rl_config(socket));
+	ricoh_set_clkrun(socket, true);
 }
 
 
···
 	config_writew(socket, RL5C4XX_CONFIG, config);
 
 	ricoh_set_zv(socket);
+	ricoh_set_clkrun(socket, false);
 
 	return 0;
 }

drivers/pcmcia/yenta_socket.c

···
 
 static bool disable_clkrun;
 module_param(disable_clkrun, bool, 0444);
-MODULE_PARM_DESC(disable_clkrun, "If PC card doesn't function properly, please try this option");
+MODULE_PARM_DESC(disable_clkrun,
+		 "If PC card doesn't function properly, please try this option (TI and Ricoh bridges only)");
 
 static bool isa_probe = 1;
 module_param(isa_probe, bool, 0444);