arch/arm/mach-omap2/am33xx/clk_synthesizer.c

   1 /*
   2  * clk-synthesizer.c
   3  *
   4  * Clock synthesizer apis
   5  *
   6  * Copyright (C) 2016, Texas Instruments, Incorporated - http://www.ti.com/
   7  *
   8  * SPDX-License-Identifier:     GPL-2.0+
   9  */
  10
  11
  12 #include <common.h>
  13 #include <asm/arch/clk_synthesizer.h>
  14 #include <i2c.h>
  15
  16 /**
  17  * clk_synthesizer_reg_read - Read register from synthesizer.
  18  * @addr:       addr within the i2c device
  19  * buf:         Buffer to which value is to be read.
  20  *
  21  * For reading the register from this clock synthesizer, a command needs to
  22  * be send along with enabling byte read more, and then read can happen.
  23  * Returns 0 on success
  24  */
  25 static int clk_synthesizer_reg_read(int addr, uint8_t *buf)
  26 {
  27         int rc;
  28
  29         /* Enable Bye read */
  30         addr = addr | CLK_SYNTHESIZER_BYTE_MODE;
  31
  32         /* Send the command byte */
  33         rc = i2c_write(CLK_SYNTHESIZER_I2C_ADDR, addr, 1, buf, 1);
  34         if (rc)
  35                 printf("Failed to send command to clock synthesizer\n");
  36
  37         /* Read the Data */
  38         return i2c_read(CLK_SYNTHESIZER_I2C_ADDR, addr, 1, buf, 1);
  39 }
  40
  41 /**
  42  * clk_synthesizer_reg_write - Write a value to register in synthesizer.
  43  * @addr:       addr within the i2c device
  44  * val:         Value to be written in the addr.
  45  *
  46  * Enable the byte read mode in the address and start the i2c transfer.
  47  * Returns 0 on success
  48  */
  49 static int clk_synthesizer_reg_write(int addr, uint8_t val)
  50 {
  51         uint8_t cmd[2];
  52         int rc = 0;
  53
  54         /* Enable byte write */
  55         cmd[0] = addr | CLK_SYNTHESIZER_BYTE_MODE;
  56         cmd[1] = val;
  57
  58         rc = i2c_write(CLK_SYNTHESIZER_I2C_ADDR, addr, 1, cmd, 2);
  59         if (rc)
  60                 printf("Clock synthesizer reg write failed at addr = 0x%x\n",
  61                        addr);
  62         return rc;
  63 }
  64
  65 /**
  66  * setup_clock_syntherizer - Program the clock synthesizer to get the desired
  67  *                              frequency.
  68  * @data: Data containing the desired output
  69  *
  70  * This is a PLL-based high performance synthesizer which gives 3 outputs
  71  * as per the PLL_DIV and load capacitor programmed.
  72  */
  73 int setup_clock_synthesizer(struct clk_synth *data)
  74 {
  75         int rc;
  76         uint8_t val;
  77
  78         rc =  i2c_probe(CLK_SYNTHESIZER_I2C_ADDR);
  79         if (rc) {
  80                 printf("i2c probe failed at address 0x%x\n",
  81                        CLK_SYNTHESIZER_I2C_ADDR);
  82                 return rc;
  83         }
  84
  85         rc = clk_synthesizer_reg_read(CLK_SYNTHESIZER_ID_REG, &val);
  86         if (val != data->id)
  87                 return rc;
  88
  89         /* Crystal Load capacitor selection */
  90         rc = clk_synthesizer_reg_write(CLK_SYNTHESIZER_XCSEL, data->capacitor);
  91         if (rc)
  92                 return rc;
  93         rc = clk_synthesizer_reg_write(CLK_SYNTHESIZER_MUX_REG, data->mux);
  94         if (rc)
  95                 return rc;
  96         rc = clk_synthesizer_reg_write(CLK_SYNTHESIZER_PDIV2_REG, data->pdiv2);
  97         if (rc)
  98                 return rc;
  99         rc = clk_synthesizer_reg_write(CLK_SYNTHESIZER_PDIV3_REG, data->pdiv3);
 100         if (rc)
 101                 return rc;
 102
 103         return 0;
 104 }