1 // SPDX-License-Identifier: GPL-2.0+ 2 /* MDIO bus multiplexer using kernel multiplexer subsystem 3 * 4 * Copyright 2019 NXP 5 */ 6 7 #include <linux/mdio-mux.h> 8 #include <linux/module.h> 9 #include <linux/mux/consumer.h> 10 #include <linux/platform_device.h> 11 12 struct mdio_mux_multiplexer_state { 13 struct mux_control *muxc; 14 bool do_deselect; 15 void *mux_handle; 16 }; 17 18 /** 19 * mdio_mux_multiplexer_switch_fn - This function is called by the mdio-mux 20 * layer when it thinks the mdio bus 21 * multiplexer needs to switch. 22 * @current_child: current value of the mux register. 23 * @desired_child: value of the 'reg' property of the target child MDIO node. 24 * @data: Private data used by this switch_fn passed to mdio_mux_init function 25 * via mdio_mux_init(.., .., .., .., data, ..). 26 * 27 * The first time this function is called, current_child == -1. 28 * If current_child == desired_child, then the mux is already set to the 29 * correct bus. 30 */ 31 static int mdio_mux_multiplexer_switch_fn(int current_child, int desired_child, 32 void *data) 33 { 34 struct platform_device *pdev; 35 struct mdio_mux_multiplexer_state *s; 36 int ret = 0; 37 38 pdev = (struct platform_device *)data; 39 s = platform_get_drvdata(pdev); 40 41 if (!(current_child ^ desired_child)) 42 return 0; 43 44 if (s->do_deselect) 45 ret = mux_control_deselect(s->muxc); 46 if (ret) { 47 dev_err(&pdev->dev, "mux_control_deselect failed in %s: %d\n", 48 __func__, ret); 49 return ret; 50 } 51 52 ret = mux_control_select(s->muxc, desired_child); 53 if (!ret) { 54 dev_dbg(&pdev->dev, "%s %d -> %d\n", __func__, current_child, 55 desired_child); 56 s->do_deselect = true; 57 } else { 58 s->do_deselect = false; 59 } 60 61 return ret; 62 } 63 64 static int mdio_mux_multiplexer_probe(struct platform_device *pdev) 65 { 66 struct device *dev = &pdev->dev; 67 struct mdio_mux_multiplexer_state *s; 68 int ret = 0; 69 70 s = devm_kzalloc(&pdev->dev, sizeof(*s), GFP_KERNEL); 71 if (!s) 72 return -ENOMEM; 73 74 s->muxc = devm_mux_control_get(dev, NULL); 75 if (IS_ERR(s->muxc)) 76 return dev_err_probe(&pdev->dev, PTR_ERR(s->muxc), 77 "Failed to get mux\n"); 78 79 platform_set_drvdata(pdev, s); 80 81 ret = mdio_mux_init(&pdev->dev, pdev->dev.of_node, 82 mdio_mux_multiplexer_switch_fn, &s->mux_handle, 83 pdev, NULL); 84 85 return ret; 86 } 87 88 static void mdio_mux_multiplexer_remove(struct platform_device *pdev) 89 { 90 struct mdio_mux_multiplexer_state *s = platform_get_drvdata(pdev); 91 92 mdio_mux_uninit(s->mux_handle); 93 94 if (s->do_deselect) 95 mux_control_deselect(s->muxc); 96 } 97 98 static const struct of_device_id mdio_mux_multiplexer_match[] = { 99 { .compatible = "mdio-mux-multiplexer", }, 100 {}, 101 }; 102 MODULE_DEVICE_TABLE(of, mdio_mux_multiplexer_match); 103 104 static struct platform_driver mdio_mux_multiplexer_driver = { 105 .driver = { 106 .name = "mdio-mux-multiplexer", 107 .of_match_table = mdio_mux_multiplexer_match, 108 }, 109 .probe = mdio_mux_multiplexer_probe, 110 .remove_new = mdio_mux_multiplexer_remove, 111 }; 112 113 module_platform_driver(mdio_mux_multiplexer_driver); 114 115 MODULE_DESCRIPTION("MDIO bus multiplexer using kernel multiplexer subsystem"); 116 MODULE_AUTHOR("Pankaj Bansal <pankaj.bansal@nxp.com>"); 117 MODULE_LICENSE("GPL"); 118