omap-ocp2scp.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 * omap-ocp2scp.c - transform ocp interface protocol to scp protocol
  4 *
  5 * Copyright (C) 2012 Texas Instruments Incorporated - http://www.ti.com
  6 * Author: Kishon Vijay Abraham I <kishon@ti.com>
  7 */
  8
  9#include <linux/io.h>
 10#include <linux/module.h>
 11#include <linux/platform_device.h>
 12#include <linux/err.h>
 13#include <linux/pm_runtime.h>
 14#include <linux/of.h>
 15#include <linux/of_platform.h>
 16
 17#define OCP2SCP_TIMING 0x18
 18#define SYNC2_MASK 0xf
 19
 20static int omap_ocp2scp_probe(struct platform_device *pdev)
 21{
 22	int ret;
 23	u32 reg;
 24	void __iomem *regs;
 25	struct resource *res;
 26	struct device_node *np = pdev->dev.of_node;
 27
 28	if (np) {
 29		ret = of_platform_populate(np, NULL, NULL, &pdev->dev);
 30		if (ret) {
 31			dev_err(&pdev->dev,
 32			    "failed to add resources for ocp2scp child\n");
 33			goto err0;
 34		}
 35	}
 36
 37	pm_runtime_enable(&pdev->dev);
 38	/*
 39	 * As per AM572x TRM: http://www.ti.com/lit/ug/spruhz6/spruhz6.pdf
 40	 * under section 26.3.2.2, table 26-26 OCP2SCP TIMING Caution;
 41	 * As per OMAP4430 TRM: http://www.ti.com/lit/ug/swpu231ap/swpu231ap.pdf
 42	 * under section 23.12.6.2.2 , Table 23-1213 OCP2SCP TIMING Caution;
 43	 * As per OMAP4460 TRM: http://www.ti.com/lit/ug/swpu235ab/swpu235ab.pdf
 44	 * under section 23.12.6.2.2, Table 23-1213 OCP2SCP TIMING Caution;
 45	 * As per OMAP543x TRM http://www.ti.com/lit/pdf/swpu249
 46	 * under section 27.3.2.2, Table 27-27 OCP2SCP TIMING Caution;
 47	 *
 48	 * Read path of OCP2SCP is not working properly due to low reset value
 49	 * of SYNC2 parameter in OCP2SCP. Suggested reset value is 0x6 or more.
 50	 */
 51	if (!of_device_is_compatible(np, "ti,am437x-ocp2scp")) {
 52		res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 53		regs = devm_ioremap_resource(&pdev->dev, res);
 54		if (IS_ERR(regs)) {
 55			ret = PTR_ERR(regs);
 56			goto err1;
 57		}
 58
 59		pm_runtime_get_sync(&pdev->dev);
 60		reg = readl_relaxed(regs + OCP2SCP_TIMING);
 61		reg &= ~(SYNC2_MASK);
 62		reg |= 0x6;
 63		writel_relaxed(reg, regs + OCP2SCP_TIMING);
 64		pm_runtime_put_sync(&pdev->dev);
 65	}
 66
 67	return 0;
 68
 69err1:
 70	pm_runtime_disable(&pdev->dev);
 71
 72err0:
 73	of_platform_depopulate(&pdev->dev);
 74
 75	return ret;
 76}
 77
 78static void omap_ocp2scp_remove(struct platform_device *pdev)
 79{
 80	pm_runtime_disable(&pdev->dev);
 81	of_platform_depopulate(&pdev->dev);
 82}
 83
 84#ifdef CONFIG_OF
 85static const struct of_device_id omap_ocp2scp_id_table[] = {
 86	{ .compatible = "ti,omap-ocp2scp" },
 87	{ .compatible = "ti,am437x-ocp2scp" },
 88	{}
 89};
 90MODULE_DEVICE_TABLE(of, omap_ocp2scp_id_table);
 91#endif
 92
 93static struct platform_driver omap_ocp2scp_driver = {
 94	.probe		= omap_ocp2scp_probe,
 95	.remove		= omap_ocp2scp_remove,
 96	.driver		= {
 97		.name	= "omap-ocp2scp",
 98		.of_match_table = of_match_ptr(omap_ocp2scp_id_table),
 99	},
100};
101
102module_platform_driver(omap_ocp2scp_driver);
103
104MODULE_ALIAS("platform:omap-ocp2scp");
105MODULE_AUTHOR("Texas Instruments Inc.");
106MODULE_DESCRIPTION("OMAP OCP2SCP driver");
107MODULE_LICENSE("GPL v2");